content: <PAGE>   1
        As filed with the Securities and Exchange Commission on July 22, 1996
  
                                                   REGISTRATION NO. 333-
                                                                        ------
  
                         SECURITIES AND EXCHANGE COMMISSION
                               Washington, D. C. 20549
  
                             ---------------------------
  
                                      FORM S-8
  
                            REGISTRATION STATEMENT UNDER
                             THE SECURITIES ACT OF 1933
  
                             ---------------------------
  
                            GELTEX PHARMACEUTICALS, INC.
               (Exact name of registrant as specified in its charter)
  
  <TABLE>
  
  <S>                                              <C>
               DELAWARE                                       04-3136767
  (State or other jurisdiction of incorporation)   (I.R.S. Employer Identification No.)
  </TABLE>
  
           303 BEAR HILL ROAD, WALTHAM, MASSACHUSETTS 02154 (617) 290-5888
     (Address and telephone number of registrant's principal executive offices)
  
                             ---------------------------
  
                             1992 EQUITY INCENTIVE PLAN
                              (Full Title of the Plan)
  
                MARK SKALETSKY, PRESIDENT AND CHIEF EXECUTIVE OFFICER
                            GelTex Pharmaceuticals, Inc.
                                 303 Bear Hill Road
                            Waltham, Massachusetts 02154
                                   (617) 290-5888
              (Name, address and telephone number of agent for service)
  
                                   with copies to:
  
                                PETER WIRTH, ESQUIRE
                                 Palmer & Dodge LLP
                                  One Beacon Street
                             Boston, Massachusetts 02108
                                   (617) 573-0100
  
                             ---------------------------
  
  <TABLE>
                                           CALCULATION OF REGISTRATION FEE
  
  <CAPTION>
  - -----------------------------------------------------------------------------------------------------------------------------------
  Title of each class of securities to     Amount to be              Proposed             Proposed maximum          Amount of
            be registered                   registered           maximum offering        aggregate offering      registration fee
                                                                  price per share              price
  - -----------------------------------------------------------------------------------------------------------------------------------
  <S>                                  <C>                           <C>                 <C>                        <C>
  Common Stock, $0.01 par value        778,251 shares (1)                  (2)           $ 3,848,731.94(3)          $1,324.00
  - -----------------------------------------------------------------------------------------------------------------------------------
  Common Stock, $0.01 par value        927,334 shares                $14.00(4)           $12,982,676.00(4)          $4,477.00
  - -----------------------------------------------------------------------------------------------------------------------------------
  <FN>
  
  (1)      Shares subject to currently outstanding options.
  (2)      The price per share at which currently outstanding options may be exercised ranges from $.125 to $24.25 per share.
  (3)      Computed in accordance with Rule 457(h)(1) based on the price per share at which currently outstanding options may be
           exercised.
  (4)      Estimated solely for the purpose of determining the registration fee and computed pursuant to Rule 457(h) based upon the
           average of the high and low sale prices on July 17, 1996 as reported by the Nasdaq National Market System.
  </TABLE>
  
                                    Page 1 of 32
                          Exhibit Index Appears at Page 22
  
  <PAGE>   2
  
  
  
  PROSPECTUS
  
                                   490,300 Shares
  
  
                            GELTEX PHARMACEUTICALS, INC.
  
  
                                    Common Stock
  
                               ----------------------
  
       This Prospectus relates to the offer and sale (the "Offering") of up to
  490,300 shares (the "Shares") of Common Stock, $.01 par value per share (the
  "Common Stock"), of GelTex Pharmaceuticals, Inc. ("GelTex" or the "Company").
  The Shares may be offered by certain stockholders of the Company identified
  herein and their pledgees, donees, transferees or other successors in interest
  (the "Selling Stockholders") from time to time in transactions on the Nasdaq
  National Market System, in privately negotiated transactions, or by a
  combination of such methods of sale, at fixed prices that maybe changed, at
  market prices prevailing at the time of sale, at prices related to such
  prevailing market prices or at negotiated prices. The Selling Stockholders may
  effect such transactions by selling the Shares to or through broker-dealers and
  such broker-dealers may receive compensation in the form of discounts,
  concessions or commissions form the Selling Stockholders or the purchasers of
  the Shares for whom such broker-dealer may act as agent or to whom they sell as
  principal or both (which compensation to a particular broker-dealer might be in
  excess of customary commissions). See "Selling Stockholders" and "Plan of
  Distribution."
  
       None of the proceeds from the sale of the Shares by the Selling
  Stockholders will be received by the Company. The Company will bear certain
  expenses (other than fees and expenses, if any, of more than one counsel or
  advisors to the Selling Stockholders) in connection with the registration and
  sale of the Shares being offered by the Selling Stockholders.
  
       The Common Stock is quoted on the Nasdaq National Market under the symbol
  "GELX." On July 18, 1996, the last sale price of the Company's Common Stock was
  $14.50 per share. See "Price Range of Common Stock."
  
                               ----------------------
  
              THE COMMON STOCK OFFERED HEREBY INVOLVES A HIGH DEGREE OF
          RISK. SEE "RISK FACTORS" BEGINNING ON PAGE 6 OF THIS PROSPECTUS.
  
                               ----------------------
  
  THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
  EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION NOR HAS THE SECURITIES
  AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION PASSED UPON THE
  ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A
  CRIMINAL OFFENSE.
  
  NO PERSON IS AUTHORIZED IN CONNECTION WITH ANY OFFERING MADE HEREBY TO GIVE ANY
  INFORMATION OR TO MAKE ANY REPRESENTATIONS OTHER THAN AS CONTAINED IN THIS
  PROSPECTUS, AND, IF GIVEN OR MADE, SUCH INFORMATION OR REPRESENTATIONS MUST NOT
  BE RELIED UPON AS HAVING BEEN AUTHORIZED BY THE COMPANY. THIS PROSPECTUS IS NOT
  AN OFFER TO SELL, OR A SOLICITATION OF AN OFFER TO BUY, BY PERSON IN ANY
  JURISDICTION IN WHICH IT IS UNLAWFUL FOR SUCH PERSON TO MAKE SUCH AN OFFER OR
  SOLICITATION. NEITHER THE DELIVERY OF THIS PROSPECTUS NOR ANY SALES MADE
  HEREUNDER SHALL UNDER ANY CIRCUMSTANCES CREATE ANY IMPLICATION THAT THE
  INFORMATION CONTAINED HEREIN IS CORRECT AS OF ANY TIME SUBSEQUENT TO THE DATE
  HEREOF.
                    The date of this Prospectus is July 19, 1996.
  
  
  <PAGE>   3
  
                                AVAILABLE INFORMATION
  
       The Company has filed with the Securities and Exchange Commission (the
  "Commission") a Registration Statement under the Securities Act of 1933, as
  amended, with respect to the shares of Common Stock offered hereby. This
  Prospectus does not contain all of the information set forth in the Registration
  Statement and the exhibits and schedules thereto. For further information with
  respect to the Company and the Common Stock offered hereby, reference is made to
  such Registration Statement and the exhibits and schedules thereto. Statements
  made in this Prospectus as to the contents of any contract, agreement or other
  document filed as an exhibit to the Registration Statement are not necessarily
  complete, and in each such instance reference is made to the copy of such
  document filed as an exhibit to the Registration Statement, each such statement
  being deemed qualified in its entirety by such reference. A copy of the
  Registration Statement may be inspected without charge at the offices of the
  Commission, 450 Fifth Street, N.W., Washington, D.C. 20549, and copies of all or
  any part thereof may be obtained from the Commission upon the payment of certain
  fees prescribed by the Commission.
  
  
                               ----------------------
  
  
                  INCORPORATION OF CERTAIN INFORMATION BY REFERENCE
  
       The following documents filed with the Securities and Exchange Commission
  (the "Commission") are incorporated herein by reference:
  
       (a) The Registrant's Annual Report on Form 10-K for the fiscal year ended
  December 31, 1995 (File No. 0-26872) filed with the Commission on March 29,
  1996.
  
       (b) The Registrant's Quarterly Report on Form 10-Q for the fiscal quarter
  ended March 31, 1996 (File No. 0-26872) filed with the Commission on May 13,
  1996.
  
       (c) The Registrant's Current Reports on Form 8-K dated March 1, 1996 and
  June 26, 1996 (File No. 0-26872) filed with the Commission on March 4, 1996 and
  June 28, 1996, respectively.
  
       (d) The Registrant's report on Form 10-C dated May 14, 1996 (File No.
  0-26872) filed with the Commission on May 17, 1996.
  
       (e) All other reports of the Registrant filed pursuant to Section 13(a) or
  15(d) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"),
  since the end of the fiscal year covered by the annual report referred to in (a)
  above.
  
       (f) The description of the Registrant's Common Stock contained in its
  Registration Statement on Form 8-A (File No. 0-26872) filed with the Commission
  on September 26, 1995, as amended on October 12, 1995, including any amendment
  or report filed hereafter for the purpose of updating such description.
  
       All documents filed after the date of this Registration Statement by the
  Registrant pursuant to Section 13(a), 13(d), 14 and 15(d) of the Exchange Act
  and prior to the filing of a post-effective amendment that indicates that all
  shares of Common Stock offered hereunder have been sold or which deregisters all
  shares of Common Stock remaining unsold shall be deemed to be incorporated by
  reference herein and to be a part hereof from the date of the filing of such
  reports and documents.
  
       The Company will furnish without charge to each person, including
  beneficial owners, to whom this Prospectus is delivered, on written or oral
  request, copies of the documents incorporated in this Prospectus by reference,
  other than exhibits to such documents. Requests should be directed to Sarah P.
  Cecil, Attorney, GelTex Pharmaceuticals, Inc., 303 Bear Hill Road, Waltham,
  Massachusetts 02154 (telephone: 617-290-5888).
  
  
                                        - 3 -
  
  <PAGE>   4
  
  
  
                                  TABLE OF CONTENTS
  
  
                                                                     Page
                                                                     ----
  
  The Company...................................................        5
  
  Risk Factors..................................................        6
  
  Selling Stockholders..........................................       12
  
  Plan of Distribution..........................................       15
  
  Legal Matters.................................................       15
  
  Experts.......................................................       15
  
  
                                        - 4 -
  
  <PAGE>   5
  
  
  
                                     THE COMPANY
  
  
          GelTex Pharmaceuticals, Inc. ("GelTex" or the "Company") is developing
  non-absorbed, polymer-based pharmaceuticals that selectively bind to and
  eliminate target substances from the intestinal tract. In March 1996, GelTex
  successfully completed a Phase IIa clinical trial of CholestaGel[Registered
  Trademark] non-absorbed cholesterol reducer, for the treatment of elevated
  cholesterol levels. This double-blind, placebo-controlled, dose ranging trial
  demonstrated a clinically and statistically significant reduction in LDL
  cholesterol levels in patients with hyperchlosteralemia (elevated cholesterol).
  The preliminary results indicate that CholestaGel may be four to five times
  more potent than cholestyramine, the most widely prescribed non-absorbed
  cholesterol-reducing drug, and appears to be well tolerated. The Company
  initiated a Phase IIb clinical trial in subjects with elevated LDL cholesterol
  in June 1996, and additional Phase II trials investigating dose scheduling and
  combination therapies are planned. Also, the Company completed, in April 1996,
  a Phase IIb clinical trial of RenaGel[Registered Trademark] phosphate binder,
  for the control of elevated phosphorus levels in chronic kidney failure
  patients. The Company initiated Phase III clinical trials for RenaGel in June
  1996. The Company is also conducting research to develop non-absorbed,
  polymer-based pharmaceuticals for the treatment of certain infections of the
  intestinal tract, such as those caused by Cryptosporidium parvum and human
  rotavirus.
  
       GelTex's pharmaceuticals act in the intestinal tract without absorption
  into the bloodstream, thereby minimizing the potential for adverse effects. The
  Company's product development approach represents an advance in the use of
  polymer hydrogels as pharmaceuticals. The Company's technology combines an
  understanding of chemical interactions necessary for molecular recognition with
  the ability to design and synthesize polymer hydrogels. The Company's technology
  enables it to combine commercially available monomers that have distinct
  structural qualities to create proprietary, non-absorbed polymers that
  selectively bind target molecules. The Company designs its polymers to carry a
  high density of selective binding sites for the targeted molecules, making them
  potent at low dosage levels and permitting oral administration in a convenient
  capsule form.
  
       GelTex is developing CholestaGel, an orally administered, non-absorbed
  hydrogel intended to reduce elevated LDL cholesterol levels in patients with
  hypercholesterolemia. The Company believes that the structural design of
  CholestaGel represents a significant advance over existing bile acid
  sequestrants in that its high density of bile acid binding sites makes it more
  potent at lower doses than currently marketed agents. The Company expects
  CholestaGel to address the need for a non-absorbed cholesterol-reducing drug
  that is safe and well tolerated in long term use, effective at low doses and
  available in a convenient capsule form.
  
       GelTex is developing RenaGel, an orally administered, non-absorbed hydrogel
  intended to control elevated blood phosphorus levels in patients with chronic
  kidney failure. RenaGel is designed to provide significant advantages over
  currently available calcium- and aluminum-based phosphate binders. RenaGel binds
  dietary phosphate without the use of either calcium or aluminum and, therefore,
  will not cause dangerous elevated blood calcium levels or aluminum toxicities.
  The Company intends to supply RenaGel in a convenient capsule form that is more
  palatable than the chalky chewable and acidic uncoated tablet forms of currently
  available phosphate binders. [In a Phase IIa clinical trial completed in August
  1995, designed to show equivalent potency to currently available calcium-based
  phosphate binders, RenaGel demonstrated such potency and was shown to be safe
  and well tolerated by dialysis patients. The Phase IIb clinical trial completed
  in April 1996 demonstrated that RenaGel significantly decreased serum phosphorus
  without increasing serum calcium.] In December 1994, GelTex granted Chugai
  Pharmaceutical Co., Ltd. an exclusive license to develop and commercialize
  RenaGel in Japan and other Pacific Rim countries.
  
       The Company's infectious disease program is directed toward developing
  non-absorbed polymers that bind, inactivate and remove specific pathogens from
  the intestinal tract. GelTex is initially focusing on two pathogens that cause
  debilitating diarrhea and for which no drug treatment currently exists:
  Cryptosporidium parvum, a parasite which causes chronic diarrhea in
  immunocompromised patients; and human rotavirus, which causes diarrhea in
  children.
  
       The Company believes its enabling technology is applicable to a broad range
  of diseases and conditions treatable through the intestinal tract. Specifically,
  the Company believes that conditions such as ulcers and inflammatory bowel
  diseases, including Crohn's disease and ulcerative colitis, could be treated
  with non-absorbed, polymer-based products developed using the Company's
  technology.
  
       GelTex was incorporated in Delaware in November 1991. The Company's
  executive offices are located at 303 Bear Hill Road, Waltham, Massachusetts
  02154 and its telephone number is (617) 290-5888.
  
       CholestaGel[Registered Trademark] and RenaGel[Registered Trademark] are a
  registered trademarks of the Company.
  
                                        - 5 -
  
  <PAGE>   6
  
  
  
                                    RISK FACTORS
  
  
       An investment in the shares of Common Stock offered hereby involves a high
  degree of risk. The following factors, in addition to the other information in
  this Prospectus, should be carefully considered in evaluating the Company and
  its business before purchasing the shares of Common Stock offered hereby.
  
  
  EARLY STAGE OF DEVELOPMENT; NO PRODUCT SALES TO DATE
  
       GelTex is a development stage company, and there can be no assurance that
  its approach to the development of non-absorbed, polymer-based pharmaceuticals
  will be successful. The Company's potential products are in various stages of
  research or development and will require substantial additional development,
  preclinical and clinical testing and investment prior to commercialization.
  There can be no assurance that the Company's research and development efforts
  will be successful or that any of its potential products will be demonstrated to
  be safe, efficacious or marketable. The Company's revenues to date have
  consisted primarily of licensing fees and research revenues from corporate
  partners in connection with two development and marketing agreements. No
  revenues have been generated from product sales, and products resulting from the
  Company's research and development efforts, if any, are not expected to be
  commercially available for a number of years. No assurance can be given that the
  Company's product development efforts will be successful, that required
  regulatory approvals can be obtained, that its products can be manufactured at
  acceptable cost and with appropriate quality or that any approved products can
  be successfully marketed.
  
  CONTINUING OPERATING LOSSES
  
       As of March 31, 1996, the Company had accumulated net losses of
  approximately $13.1 million. The continuing development of the Company's
  potential products will require the commitment of substantial resources to
  conduct research, preclinical studies and clinical trials and to establish
  effective commercial manufacturing processes. The Company expects to incur
  substantial operating losses for at least the next several years as it continues
  to develop its potential products. The amount of net losses and the time
  required to reach sustained profitability are highly uncertain. To achieve
  sustained profitable operations, the Company, alone or with corporate partners,
  must successfully develop, manufacture and market its products. No assurance can
  be given that the Company will be able to achieve or sustain profitability.
  
  FUTURE CAPITAL NEEDS; UNCERTAINTY OF ADDITIONAL FUNDING
  
       Since inception, the Company has funded its operations primarily through
  the issuance of equity securities. The Company anticipates that it will need to
  raise substantial additional funds for research, development and other expenses,
  through equity or debt financings, research and development financings,
  collaborative relationships or otherwise, prior to the commercialization of any
  of its products. There can be no assurance that any such additional funding will
  be available to the Company or, if available, that it will be on reasonable
  terms. Any such additional financing may result in dilution to existing
  stockholders. If adequate funds are not available, the Company may be required
  to significantly curtail its research and development programs, including
  clinical trials, or enter into arrangements that may require the Company to
  relinquish certain material rights to its products on terms that it might
  otherwise find unacceptable.
  
  UNCERTAINTY ASSOCIATED WITH PRECLINICAL AND CLINICAL TESTING
  
       Before obtaining regulatory approvals for the commercial sale of any of its
  potential products, the products will be subjected to extensive preclinical and
  clinical testing to demonstrate their safety and efficacy in humans. To date,
  the Company has tested CholestaGel and RenaGel in limited numbers of subjects in
  Phase I and Phase II clinical trials. The results of initial preclinical and
  clinical testing of these products under development by the Company are not
  necessarily predictive of results that will be obtained from subsequent or more
  extensive preclinical and clinical testing. Furthermore, there can be no
  assurance that clinical trials of products under development will demonstrate
  the safety and efficacy of such products at all or to the extent necessary to
  obtain regulatory approvals. Companies in the biotechnology industry have
  suffered significant setbacks in advanced clinical trials, even after
  
                                        - 6 -
  
  <PAGE>   7
  
  
  
  promising results in earlier trials. The failure to adequately demonstrate the
  safety and efficacy of a therapeutic product under development could delay or
  prevent regulatory approval of the product and would have a material adverse
  effect on the Company.
  
       The rate of completion of clinical trials is dependent upon, among other
  factors, the enrollment of patients. Patient accrual is a function of many
  factors, including the size of the patient population, the proximity of patients
  to clinical sites, the eligibility criteria for the study and the existence of
  competitive clinical trials. Delays in planned patient enrollment in the
  Company's current trials or future clinical trials may result in increased
  costs, program delays or both, which could have a material adverse effect on the
  Company. There can be no assurance that if clinical trials are completed the
  Company will be able to submit a New Drug Application ("NDA") as scheduled or
  that any such application will be reviewed and approved by the United States
  Food and Drug Administration ("FDA") in a timely manner, or at all.
  
  DEPENDENCE ON CORPORATE ALLIANCES
  
       The Company expects to develop and market its potential products through
  alliances with corporate partners. The Company is currently engaged in one such
  collaboration to develop and commercialize RenaGel phosphate binder in Japan and
  other Pacific Rim countries. The Company is relying upon its partner to conduct
  clinical trials, obtain regulatory approval for the sale of the products in the
  territory covered by the agreement and manufacture and market the products in
  the territory. There can be no assurance that its partner will devote the
  resources necessary to complete development of and commence marketing for the
  products in the territory. The agreement is subject to termination without cause
  on short notice under certain circumstances and there is no assurance that in
  the future the Company's partner will not exercise its termination rights.
  
       The Company expects to enter into other development and marketing
  agreements in other territories for its potential products, and in connection
  with such agreements will rely upon corporate partners to conduct clinical
  trials, obtain regulatory approval for and manufacture and market its potential
  products. There can be no assurance that the Company will be able to establish
  agreements for the commercialization of RenaGel in other parts of the world or
  for the commercialization of the Company's other products. The termination of
  its existing agreements and the failure to secure additional development and
  marketing agreements with other corporate partners would have a material adverse
  effect on the Company's operations.
  
  DEPENDENCE ON SINGLE SOURCE OF SUPPLY; NO SUPPLY AGREEMENT
  
       The Company uses a single supplier to provide a certain raw material
  necessary for the manufacture of CholestaGel and RenaGel. The supplier has a
  composition of matter patent covering the material, and the Company believes
  that currently there are no alternative suppliers of this material. The Company
  does not have a long term, fixed price supply agreement for this raw material
  but rather obtains the raw material by issuing purchase orders to the supplier
  on an as needed basis. To date, the Company has not experienced any difficulty
  in obtaining adequate supplies of the raw material. However, no assurance can be
  given that the raw material will remain available to the Company or to its
  corporate partners in commercial quantities at acceptable costs. Should the
  Company or its corporate partners be unable to obtain an adequate supply of the
  material at commercially reasonable rates, the operations of the Company would
  be adversely affected.
  
  NO ASSURANCE OF FDA APPROVAL; COMPREHENSIVE GOVERNMENT REGULATION
  
       The Company's research, development and clinical programs, as well as the
  operations of its third party manufacturers and the marketing operations of its
  corporate partners, are subject to extensive regulation by numerous governmental
  authorities in the United States and other countries. The Company's potential
  products require governmental approvals for commercialization, which have not
  yet been obtained and are not expected to be obtained for several years. The
  regulatory process, which includes preclinical, clinical and, in certain
  instances, post-marketing testing to establish safety and efficacy, can take
  many years and require the expenditure of substantial resources. The Company has
  had only limited experience in conducting preclinical testing and human clinical
  trials and obtaining FDA and other regulatory approvals. Data obtained from
  preclinical and clinical activities are susceptible to varying interpretations,
  which could delay, limit or prevent regulatory approval. In addition, delays or
  rejection may be encountered based upon changes in, or additions to, regulatory
  policies for drug approval during
  
                                        - 7 -
  
  <PAGE>   8
  
  
  
  the period of product development and regulatory review. Delays in obtaining
  such approvals could adversely affect the marketing of products developed by the
  Company and the Company's ability to generate commercial product revenues. There
  can be no assurance that requisite regulatory approvals will be obtained within
  a reasonable period of time, if at all. Moreover, if regulatory approval of a
  product is granted, such approval may impose limitations on the indicated uses
  for which such product may be marketed. Further, even if such regulatory
  approval is obtained, a marketed product, its manufacturer and its manufacturing
  facilities are subject to continual review and periodic inspections, and later
  discovery of previously unknown problems with a product, manufacturer or
  facility may result in restrictions on such product or manufacturer, including
  withdrawal of the product from the market. Failure to comply with the applicable
  regulatory requirements can, among other things, result in fines, suspensions of
  regulatory approvals, product recalls, operating restrictions and criminal
  prosecution. The Company is also subject to numerous environmental, health and
  workplace safety laws and regulations, including those governing laboratory
  procedures and the handling of biohazardous materials. Any violation of, and
  cost of compliance with, these laws and regulations could adversely affect the
  Company's operations.
  
  TECHNOLOGICAL CHANGE; COMPETITION
  
       The biotechnology and pharmaceutical industries are subject to rapid and
  significant technological change. Competitors of GelTex in the United States and
  abroad are numerous and include, among others, pharmaceutical and biotechnology
  companies, universities and other research institutions. The Company's success
  depends upon developing and maintaining a competitive position in the
  development of products and technologies in its areas of focus. There can be no
  assurance that the Company's competitors will not succeed in developing
  technologies and products that are more effective than any which are being
  developed by the Company or which would render the Company's technology and
  products obsolete or noncompetitive. Many of these competitors have
  substantially greater financial and technical resources and production and
  marketing capabilities than the Company, and certain of these competitors may
  compete with the Company in establishing development and marketing agreements
  with pharmaceutical companies. In addition, many of the Company's competitors
  have greater experience than the Company in conducting preclinical testing and
  human clinical trials and obtaining FDA and other regulatory approvals. The
  Company's competitors may succeed in obtaining FDA approval for products more
  rapidly than the Company.
  
       The pharmaceutical industry is intensely competitive. Many companies,
  including biotechnology, chemical and pharmaceutical companies, are actively
  engaged in activities similar to those of the Company, including research and
  development of products for hypercholesterolemia, hyperphosphatemia,
  cryptosporidiosis and human rotavirus infection. In the cholesterol-reduction
  field, products are currently available that address some of the needs of the
  market. These products include other bile acid sequestrants, HMG-CoA reductase
  inhibitors, fibric acid derivatives and niacin. In 1994, sales of HMG-CoA
  reductase inhibitors represented approximately 68% of the market for
  cholesterol-reducing drugs sold in the United States. Worldwide sales of the
  three leading HMG-CoA reductase inhibitors each exceeded $1 billion in 1995.
  Several phosphate binders are also currently available. A prescription calcium
  acetate preparation is currently the only product approved in the United States
  for the control of elevated phosphorus levels in patients with chronic kidney
  failure. Other products used as phosphate binders include over-the-counter
  calcium- and aluminum-based antacids and dietary calcium supplements. While the
  Company believes that its products will offer significant advantages over
  available agents, currently marketed products often have a significant
  competitive advantage over new entrants. There can be no assurance that the
  Company's products under development will be able to compete successfully with
  existing therapies or with products under development by other companies,
  universities and other institutions.
  
  DEPENDENCE ON PATENTS AND PROPRIETARY TECHNOLOGY
  
       The biotechnology and pharmaceutical industries place considerable
  importance on obtaining patent and trade secret protection for new technologies,
  products and processes. The Company's success will depend, in part, on its
  ability to obtain patent protection for its products and manufacturing
  processes, preserve its trade secrets and operate without infringing the
  proprietary rights of third parties. The Company has ongoing research efforts
  and expects to seek additional patents covering this research in the future.
  There can be no assurance of its success or timeliness in obtaining any patents,
  or of the breadth or degree of protection that any such patents will afford the
  Company. The patent position of biotechnology and pharmaceutical products is
  often highly uncertain and usually involves complex legal and factual questions.
  There can be no assurance that patent applications relating to the
  
                                        - 8 -
  
  <PAGE>   9
  
  
  
  Company's potential products or technology will result in patents being issued
  or that any current or future patents will afford adequate protection to the
  Company or not be challenged, invalidated or infringed. Furthermore, there can
  be no assurance that others will not independently develop similar products and
  processes, duplicate any of the Company's products or, if patents are issued to
  the Company, design around such patents. In addition, the Company could incur
  substantial costs in defending itself in suits brought against it or in suits in
  which the Company may assert its patents against others. If the outcome of any
  such litigation is unfavorable to the Company, the Company's business could be
  adversely affected. To determine the priority of inventions, the Company may
  also have to participate in interference proceedings declared by the United
  States Patent and Trademark Office, which could result in substantial cost to
  the Company.
  
       In addition, the Company may be required to obtain licenses to patents or
  other proprietary rights of third parties. No assurance can be given that any
  licenses required under any such patents or proprietary rights would be made
  available on terms acceptable to the Company, if at all. If the Company does not
  obtain such licenses, it could encounter delays in product market introductions
  while it attempts to design around such patents or other rights, or it may be
  unable to develop, manufacture or sell such products.
  
       The Company also seeks to protect its proprietary technology, including
  technology which may not be patented nor patentable, in part by confidentiality
  agreements and, if applicable, inventors' rights agreement with its
  collaborators, advisors, employees and consultants. There can be no assurance
  that these agreements will not be breached, that the Company will have adequate
  remedies for any breach or that the Company's trade secrets will not otherwise
  be disclosed to, or discovered by, competitors. There can be no assurance that
  such persons or institutions will not assert rights to intellectual property
  arising out of such research.
  
  DEPENDENCE ON OTHERS FOR MANUFACTURING; PROCESS DEVELOPMENT RISKS
  
       The Company has chosen not to develop the capability to manufacture its
  potential products in clinical or commercial quantities and, therefore, must
  rely upon third party manufacturers for the production of its compounds for
  preclinical and clinical trial purposes. The Company expects to rely upon third
  party manufacturers for commercial production. In the event that the Company is
  unable to obtain contract manufacturing on commercially reasonable terms, it may
  not be able to commercialize its potential products as planned. The Company's
  dependence on third parties for the manufacture of its potential products may
  adversely affect the Company's profit margins, its ability to develop and
  manufacture products on a timely and competitive basis, the progress of clinical
  trials, the timing of market introductions and subsequent sales of such
  products.
  
       The Company has not yet established effective processes for the manufacture
  of commercial quantities of its potential products. Significant process
  development work will be required to establish such processes. There can be no
  assurance that such process development work will be successful or that the
  Company will obtain rights to use, or license its corporate partners to use,
  such commercial processes.
  
  ABSENCE OF SALES AND MARKETING EXPERIENCE
  
       The Company has no experience in sales, marketing or distribution. The
  Company plans to establish marketing arrangements with pharmaceutical companies
  with large distribution capabilities in order to market its products. As a
  result, sales of the Company's products will depend upon the efforts of third
  parties and there can be no assurance that such efforts will be successful.
  
  PRODUCT LIABILITY AND LIMITED INSURANCE
  
       The Company's business exposes it to potential product liability claims,
  which are inherent in the testing, manufacturing, marketing and sale of human
  therapeutics. The use of the Company's product candidates in clinical trials
  also exposes the Company to product liability claims and possible adverse
  publicity. These risks increase with respect to the Company's product
  candidates, if any, that receive regulatory approval for commercialization. The
  Company currently has limited product liability insurance coverage for the
  clinical research use of its product candidates. The Company does not have
  product liability coverage for the commercial sale of its products but intends
  to obtain such coverage if and when its products are commercialized. However,
  there can be no assurance
  
                                        - 9 -
  
  <PAGE>   10
  
  
  
  that the Company will be able to obtain additional insurance coverage on
  acceptable terms, if at all, or that a product liability claim would not
  materially adversely affect the business of the Company.
  
  DEPENDENCE ON REIMBURSEMENT
  
       In both domestic and foreign markets, the ability of the Company to
  commercialize its products will depend, in part, on the availability of
  reimbursement from third-party payors, such as government health administration
  authorities, private health insurers and other organizations. Third-party payors
  are increasingly challenging the price and cost effectiveness of medical
  products. There can be no assurance that the Company's potential products will
  be considered cost effective. If adequate coverage and reimbursement levels are
  not provided by the government and third-party payors for uses of the Company's
  therapeutic products, the market acceptance of these products would be adversely
  affected. This is particularly true with the respect to the Company's RenaGel
  product, which the Company anticipates will compete with certain low priced
  over-the-counter products.
  
  DEPENDENCE UPON KEY PERSONNEL
  
       The Company is highly dependent on the members of its management and
  scientific staff, the loss of one or more of whom could have a material adverse
  effect on the Company. In addition, the Company believes that its future success
  will depend in large part upon its ability to attract and retain highly skilled
  scientific and managerial personnel, particularly as the Company expands its
  activities in clinical trials and the regulatory approval process. The Company
  faces significant competition for such personnel from other companies, research
  and academic institutions, government entities and other organizations. There
  can be no assurance that the Company will be successful in hiring or retaining
  the personnel it requires for continued growth. The failure to hire and retain
  such personnel could materially and adversely affect the Company.
  
  ABSENCE OF DIVIDENDS
  
       The Company has never paid dividends and does not intend to pay any cash
  dividends in the foreseeable future.
  
  POTENTIAL VOLATILITY OF STOCK PRICE
  
       The market price of the shares of Common Stock, like that of the common
  stock of many other development stage biotechnology companies, may be highly
  volatile. Factors such as announcements of technological innovations or new
  commercial products by the Company or its competitors, disclosure of results of
  clinical testing or regulatory proceedings, governmental regulation and
  approvals, developments in patent or other proprietary rights, public concern as
  to the safety of products developed by the Company and general market conditions
  may have a significant effect on the market price of the Common Stock. In
  addition, the stock market has experienced extreme price and volume
  fluctuations. This volatility has significantly affected the market prices of
  securities of many biotechnology and pharmaceutical companies for reasons
  frequently unrelated to or disproportionate to the operating performance of the
  specific companies. These broad market fluctuations may adversely affect the
  market price of the Company's Common Stock.
  
  CONTROL BY EXISTING STOCKHOLDERS
  
       As of June 30, 1996, the Company's directors, executive officers and 5%
  stockholders and certain of their affiliates beneficially own approximately 49%
  of the outstanding shares of the Common Stock. Accordingly, they have the
  ability to control the election of the Company's directors and significantly
  influence or control other stockholder actions.
  
  ANTI-TAKEOVER PROVISIONS
  
       The Company's Restated Certificate of Incorporation, and Amended and
  Restated By-laws of the Company contain provisions that could discourage
  potential takeover attempts and prevent stockholders from changing the Company's
  management. The Company's Restated Certificate of Incorporation authorizes the
  Board to issue shares of preferred stock without further action by the
  stockholders. The Company's Restated Certificate of Incorporation
  
                                       - 10 -
  
  <PAGE>   11
  
  
  
  also includes provisions (i) classifying the Board of Directors into three
  classes with staggered three-year terms, (ii) prohibiting stockholder action by
  written consent except as otherwise provided by law and (iii) requiring the
  approval of the holders of two-thirds of the Company's capital stock for certain
  transactions. The Company's Bylaws also provide that special meetings of the
  Company's stockholders may be called only by the President or the directors and
  require advance notice of business to be brought by a stockholder before the
  annual meeting. The Company has also adopted a stockholders rights plan. The
  stockholders rights plan together with the aforementioned charter and by-law
  provisions may discourage certain types of transactions involving an actual or
  potential change in control of the Company, including transactions in which the
  stockholders might otherwise receive a premium for their shares over then
  current prices, and may limit the ability of the stockholders to approve
  transactions they may deem to be in their best interest. In addition, the Board
  of Directors has the authority, without action by the stockholders, to fix the
  rights and preferences of and to issue shares of preferred stock which also may
  have the effect of delaying or preventing a change in control of the Company.
  
  
                                       - 11 -
  
  <PAGE>   12
  
  
  
                                SELLING STOCKHOLDERS
  <TABLE>
  
       The Shares being offered hereby were acquired by the persons listed in the
  table below pursuant to stock option exercises under the Company's 1992 Equity
  Incentive Plan. The table below sets forth the number of Shares held as of July
  10, 1996 by affiliates and non-affiliates of the Company. All of the Shares are
  being registered for resale pursuant to a Registration Statement on Form S-8, of
  which this Prospectus is a part. Selling Stockholders may offer the Shares for
  resale from time to time. See "Plan of Distribution."
  <CAPTION>
  
                                         Shares Owned Prior                                      Shares Owned After
                                           to Offering(1)                                           Offering(1)
                                        --------------------        Number of Shares             ------------------
  Selling Stockholder                   Number       Percent          Being Offered              Number    Percent
  - -------------------                   ------       -------        ----------------             ------    -------
  <S>                                   <C>                <C>          <C>                      <C>            <C>
  Peter M. Ahern                           500             *               500                       --         --
  Robert C. Blanks                      14,000 (2)         *            14,000 (2)                   --         --
  Suanne Bodenrader                      1,000 (3)         *             1,000 (3)                   --         --
  Charles H. Boyd                        3,000 (4)         *             3,000 (4)                   --         --
  Steven K. Burke                       50,000 (5)         *            50,000 (5)                   --         --
  Xi Chen                                3,000 (6)         *             3,000 (6)                   --         --
  Lisa A. D'Attanasio                    3,000 (7)         *             3,000 (7)                   --         --
  Eileen M. Doyle                        3,000 (8)         *             3,000 (8)                   --         --
  Leslie Fay-Warris                      1,516             *             1,516                       --         --
  Venkata Garigpati                     15,000 (9)         *            15,000 (9)                   --         --
  Dennis I. Goldberg                    75,000 (10)        *            75,000 (10)                  --         --
  Alan Hofmann                           7,000             *             7,000                       --         --
  Stephen R. Holmes-Farley              22,400 (11)        *            22,400 (11)                  --         --
  Cynthia R. Maloney                       300             *               300                       --         --
  W. Harry Mandeville                   80,000 (12)        *            40,000 (12)              40,000          *
  Salvatore Marchese                     7,500             *             7,500                       --         --
  Karen L. Miller                        3,000 (13)        *             3,000 (13)                  --         --
  Robert J. Nicolosi                     5,000             *             5,000                       --         --
  Kenneth A. Norton                     10,850 (14)        *            10,850 (14)                  --         --
  John S. Peterson                      29,000 (15)        *            29,000 (15)                  --         --
  Mary C. Pitruzello                     4,000 (16)        *             4,000 (16)                  --         --
  David P. Rosenbaum                    25,000 (17)        *            25,000 (17)                  --         --
  Robert J. Sacchiero                    1,600             *             1,600                       --         --
  Ken Setchell                          15,000             *            15,000                       --         --
  Mark Skaletsky                        80,000 (18)        *            80,000 (18)                  --         --
  Edwin E. Sopp                          2,300 (19)        *             2,300 (19)                  --         --
  Joseph E. Tyler                       30,000 (20)        *            30,000 (20)                  --         --
  James L. Ward                          3,000 (21)        *             3,000 (21)                  --         --
  Amy K. Wilson                         25,000 (22)        *            25,000 (22)                  --         --
  Leslie A. Wyche                          834 (23)        *               834 (23)                  --         --
  Yevgeniy Zhorov                        9,500 (24)        *             9,500 (24)                  --         --
  <FN>                                                                                                       
  
  - --------------------
  *  Indicates less than 1%
  
  (1)  Unless otherwise indicated in these footnotes, each Selling Stockholder has
  sole voting and investment power with respect to the shares listed in the table.
  
  (2)  Includes 7,917 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (3)  Includes 450 Shares subject to a right of repurchase granted to the 
  Company, which will terminate as such Shares vest.
  
  (4)  Includes 1,950 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  </TABLE>
  
                                       - 12 -
  
  <PAGE>   13
  
  
  
  
  (5)  Includes 32,500 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (6)  Includes 1,700 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (7)  Includes 2,050 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (8)  Includes 1,550 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (9)  Includes 7,500 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (10)  Includes 37,500 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (11)  Includes 5,917 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (12)  Includes 18,750 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (13)  Includes 1,101 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (14)  Includes 6,850 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (15)  Includes 17,234 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (16)  Includes 2,217 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (17)  Includes 14,167 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (18)  Includes 10,000 Shares held by Mr. Skaletsky's wife and 6,000 Shares held 
  by his children.
  
  (19)  Includes 1,600 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (20)  Includes 18,334 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (21)  Includes 1,500 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (22)  Includes 12,250 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (23)  Includes 767 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  
                                       - 13 -
  
  <PAGE>   14
  
  
  
  (24)  Includes 6,834 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  
       The following Selling Stockholders are officers of the Company: Mark B.
  Skaletsky, President, Chief Financial Officer and Treasurer; Dennis Goldberg,
  Vice President, Product Development and Regulatory Affairs; W. Harry Mandeville,
  Vice President, Chemical Technology; and Joseph Tyler, Vice President,
  Manufacturing.
  
                                       - 14 -
  
  <PAGE>   15
  
  
  
  
                                PLAN OF DISTRIBUTION
  
       The Company has filed with the Commission under the Securities Act of 1933,
  as amended (the "Securities Act"), a Registration Statement on Form S-8, of
  which this Prospectus forms a part, with respect to the resale of the Shares
  from time to time on the Nasdaq National Market System or in
  privately-negotiated transactions.
  
       The Company has been advised that the Selling Stockholders may sell the
  Shares from time to time in transactions on the Nasdaq National Market System,
  in privately negotiated transactions, or by a combination of such methods of
  sale, at fixed prices that maybe changed, at market prices prevailing at the
  time of sale, at prices related to such prevailing market prices or at
  negotiated prices. The Selling Stockholders may effect such transactions by
  selling the Shares to or through broker-dealers and such broker-dealers may
  receive compensation in the form of discounts, concessions or commissions from
  the Selling Stockholders or the purchasers of the Shares for whom such
  broker-dealer may act as agent or to whom they sell as principal or both (which
  compensation to a particular broker-dealer might be in excess of customary
  commissions). The amount of Shares to be sold hereunder by each Selling
  Stockholder and any other person with whom he or she is acting in concert for
  the purpose of selling securities of the Company may not exceed, during any
  three-month period, the amount specified in Rule 144(e) under the Securities
  Act.
  
       The Selling Stockholders and any broker-dealer who acts in connection with
  the sale of Shares hereunder may be deemed to be "underwriters" as that term is
  defined in the Securities Act, and any commissions received by them and profit
  on any resale of the Shares as principal might be deemed to be underwriting
  discounts and commissions under the Securities Act.
  
       The Selling Stockholders may also sell Shares from time to time in
  accordance with Rule 144 or Rule 701 under the Securities Act.
  
  
  
                                    LEGAL MATTERS
  
  
       The validity of the shares of Common Stock offered hereby will be passed
  upon for the Company by Palmer & Dodge LLP, Boston, Massachusetts. Peter Wirth,
  a partner of Palmer & Dodge LLP, is Secretary of the Company.
  
  
                                       EXPERTS
  
  
       The financial statements of GelTex Pharmaceuticals, Inc. appearing in
  GelTex Pharmaceuticals, Inc.'s Annual Report (Form 10-K) for the year ended
  December 31, 1995 have been audited by Ernst & Young LLP, independent auditors,
  as set forth in their report thereon included therein and incorporated herein by
  reference. Such financial statements are incorporated herein by reference in
  reliance upon such report given upon the authority of such firm as experts in
  accounting and auditing.
  
  
                                       - 15 -
  
  <PAGE>   16
  
  
  
                                       PART II
                 INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
  
  
  Item 3.  Incorporation of Documents by Reference.
  - ------------------------------------------------
  
       The following documents filed with the Securities and Exchange Commission
  (the "Commission") are incorporated herein by reference:
  
       (a) The Registrant's Annual Report on Form 10-K for the fiscal year ended
  December 31, 1995 (File No. 0-26872) filed with the Commission on March 29,
  1996.
  
       (b) The Registrant's Quarterly Report on Form 10-Q for the fiscal quarter
  ended March 31, 1996 (File No. 0-26872) filed with the Commission on May 13,
  1996.
  
       (c) The Registrant's Current Reports on Form 8-K dated March 1, 1996 and
  June 26, 1996 (File No. 0-26872) filed with the Commission on March 4, 1996 and
  June 28, 1996, respectively.
  
       (d) The Registrant's report on Form 10-C dated May 14, 1996 (File No.
  0-26872) filed with the Commission on May 17, 1996.
  
       (e) All other reports of the registrant filed pursuant to Section 13(a) or
  15(d) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"),
  since the end of the fiscal year covered by the annual report referred to in (a)
  above.
  
       (f) The description of the Registrant's Common Stock contained in its
  Registration Statement on Form 8-A (File No. 0-26872) filed with the Commission
  on September 26, 1995, as amended on October 12, 1995, including any amendment
  or report filed hereafter for the purpose of updating such description.
  
       All documents filed after the date of this Registration Statement by the
  Registrant pursuant to Section 13(a), 13(d), 14 and 15(d) of the Exchange Act
  and prior to the filing of a post-effective amendment that indicates that all
  shares of Common Stock offered hereunder have been sold or which deregisters all
  shares of Common Stock remaining unsold shall be deemed to be incorporated by
  reference herein and to be a part hereof from the date of the filing of such
  reports and documents.
  
  
  Item 4.  Description of Securities.
  - ----------------------------------
  
           Not applicable.
  
  
  Item 5.  Interests of Named Experts and Counsel.
  - -----------------------------------------------
  
       The validity of the Common Stock offered hereby will be passed upon for the
  Registrant by Palmer & Dodge LLP, Boston, Massachusetts. Peter Wirth, a partner
  of Palmer & Dodge LLP, is Secretary of the Registrant.
  
  
                                       - 16 -
  
  <PAGE>   17
  
  Item 6. Indemnification of Directors and Officers
  - -------------------------------------------------
  
       Section 145 of the Delaware General Corporation Law permits the Registrant
  to indemnify directors, officers, employees and agents of the Registrant against
  actual and reasonable expenses (including attorneys' fees) incurred by them in
  connection with any action, suit or proceeding brought against them by reason of
  their status or service as a director, officer, employee or agent by or on
  behalf of the Registrant, and against expenses (including attorneys' fees),
  judgments, fines and settlements actually and reasonably incurred by him in
  connection with any such action, suit or proceeding, if (i) he acted in good
  faith and in a manner he reasonably believed to be in or not opposed to the best
  interests of the Registrant, and (ii) in the case of a criminal proceeding, he
  had no reasonable cause to believe his conduct was unlawful. Except as ordered
  by a court, no indemnification shall be made in connection with any proceeding
  brought by or in the right of the corporation where the person involved is
  adjudged to be liable to the Registrant.
  
       Article EIGHTH of the Registrant's Restated Certificate of Incorporation
  provides that a director shall not be personally liable to the Registrant or its
  stockholders for monetary damages for breach of fiduciary duty as a director,
  except to the extent that elimination or limitation of liability is not
  permitted under the Delaware General Corporation Law as in effect when such
  liability is determined.
  
       Article NINTH of the Registrant's Restated Certificate of Incorporation
  provides that the Registrant shall, to the fullest extent permitted by the
  General Corporation Law of the State of Delaware, as amended from time to time,
  indemnify each person who was or is a party or is threatened to be made a party
  to any threatened, pending or completed action, suit or proceeding whether
  civil, criminal, administrative or investigative, by reason of the fact that he
  is or was, or has agreed to become a director or officer of the Registrant, or
  is or was serving, or has agreed to serve at the request of the Registrant as a
  director, officer or trustee of, or in a similar capacity with, another
  corporation, partnership, joint venture, trust or other enterprise. The
  indemnification provided for in Article NINTH is expressly not exclusive of any
  other rights to which those seeking indemnification may be entitled under any
  law, agreement or vote of stockholders or disinterested directors or otherwise,
  and shall inure to the benefit of the heirs, executors and administrators of
  such persons. Article NINTH further permits the Board of Directors to authorize
  the grant of indemnification rights to other employees and agents of the
  Registrant and such rights may be equivalent to, or greater or less than, those
  set forth in Article NINTH.
  
       Article V, Section 1 of the Registrant's By-Laws provides that the
  Registrant shall have the power to purchase and maintain insurance on behalf of
  any person who is or was a director, officer, employee or agent of the
  Registrant, or is or was serving at the request of the Registrant as a director,
  officer, employee or agent of another corporation, partnership, joint venture,
  trust or other enterprise against any liability asserted against such person and
  incurred by such person in any such capacity or arising out of such person's
  status as such.
  
       The Registrant maintains insurance for directors and officers and expects
  to enter into agreements with certain officers and directors affirming the
  Registrant's obligation to indemnify them to the fullest extent permitted by law
  and providing various other protections.
  
  
  Item 7. Exemption from Registration Claimed.
  - -------------------------------------------
  
           Not applicable.
  
                                       - 17 -
  
  <PAGE>   18
  
  
  Item 8. Exhibits.
  - ----------------
  
       Exhibit Number                         Description
       --------------                         -----------
  
            4.1       Restated Certificate of Incorporation of the Registrant.
                      Filed as Exhibit 4.1 to the Company's Registration Statement
                      on Form S-8 (File No. 333-6779) and incorporated herein by
                      reference.
  
            4.2       Amended and Restated By-laws of the Registrant. Filed as
                      Exhibit 3.3 to the Company's Annual Report on Form 10-K for
                      the fiscal year ended December 31, 1995 and incorporated
                      herein by reference.
  
            4.3       Rights Agreement dated as of March 1, 1996 between the
                      Company and American Stock Transfer & Trust Company. Filed
                      as Exhibit 1 to the Company's Registration Statement on Form
                      8-A dated March 1, 1996 and incorporated herein by
                      reference.
  
            5.1       Opinion of Palmer & Dodge LLP as to the legality of the
                      securities registered hereunder.
  
           23.1       Consent of Ernst & Young LLP, independent auditors.
  
           23.2       Consent of Palmer & Dodge LLP (contained in Opinion of
                      Palmer & Dodge LLP, filed as Exhibit 5.1 hereto).
  
           24.1       Power of Attorney (set forth on the signature page to this
                      Registration Statement).
  
           24.2       Certified resolution of the Board of Directors authorizing
                      Power of Attorney.
  
           99.1       1992 Equity Incentive Plan, as amended through May 20, 1996.
  
  
  Item 9.  Undertakings.
  - ---------------------
  
       (a) The undersigned Registrant hereby undertakes:
  
           (1) To file, during any period in which offers or sales are being 
  made, a post-effective amendment to this registration statement:
  
               (i) To include any prospectus required by Section 10(a)(3) of the
  Securities Act of 1933;
  
               (ii) To reflect in the prospectus any facts or events arising 
  after the effective date of this Registration Statement (or the most recent
  post-effective amendment thereof) which, individually or in the aggregate,
  represents a fundamental change in the information set forth in this
  Registration Statement;
  
               (iii) To include any material information with respect to the 
  plan of distribution not previously disclosed in this Registration Statement or
  any material change to such information in this Registration Statement;
  
                                       - 18 -
  
  <PAGE>   19
  
  
  
  PROVIDED, HOWEVER, that paragraphs (a)(1)(i) and (a)(1)(ii) do not apply if the
  information required to be included in a post-effective amendment by those
  paragraphs is contained in periodic reports filed by the Registrant pursuant to
  Section 13 or Section 15(d) of the Securities Exchange Act of 1934 that are
  incorporated by reference in this Registration Statement.
  
           (2) That, for the purpose of determining any liability under the 
  Securities Act of 1933, each such post-effective amendment shall be deemed to be
  a new registration statement relating to the securities offered therein, and the
  offering of such securities at that time shall be deemed to be the initial bona
  fide offering thereof.
  
           (3) To remove from registration by means of a post-effective amendment
  any of the securities being registered which remain unsold at the termination of
  the offering.
  
       (b) The undersigned Registrant hereby undertakes that, for purposes of
  determining any liability under the Securities Act of 1933, each filing of the
  Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
  Securities Exchange Act of 1934 that is incorporated by reference in this
  Registration Statement shall be deemed to be a new registration statement
  relating to the securities offered therein, and the offering of such securities
  at that time shall be deemed to be the initial bona fide offering thereof.
  
       (c) Insofar as indemnification for liabilities arising under the Securities
  Act of 1933 may be permitted to directors, officers and controlling persons of
  the Registrant pursuant to the provisions referred to in Item 6 hereof, or
  otherwise, the Registrant has been advised that in the opinion of the Securities
  and Exchange Commission such indemnification is against public policy as
  expressed in the Act and is, therefore, unenforceable. In the event that a claim
  for indemnification against such liabilities (other than the payment by the
  Registrant of expenses incurred or paid by a director, officer or controlling
  person of the registrant in the successful defense of any action, suit or
  proceeding) is asserted by such director, officer or controlling person in
  connection with the securities being registered, the Registrant will, unless in
  the opinion of its counsel the matter has been settled by controlling precedent,
  submit to a court of appropriate jurisdiction the question whether such
  indemnification by it is against public policy as expressed in the Act and will
  be governed by the final adjudication of such issue.
  
  
                                       - 19 -
  
  <PAGE>   20
  
  
                                     SIGNATURES
  
       Pursuant to the requirements of the Securities Act of 1933, the Registrant
  certifies that it has reasonable grounds to believe that it meets all of the
  requirements for filing on Form S-8 and has duly caused this Registration
  Statement to be signed on its behalf by the undersigned, thereunto duly
  authorized, in the City of Waltham, State of Massachusetts, on this 19th day of
  July, 1996.
  
                                        GELTEX PHARMACEUTICALS, INC.
  
  
                                        By: /s/ Mark Skaletsky
                                            -------------------------------------
                                            Mark Skaletsky
                                            President and Chief Executive Officer
  
  
                                  POWER OF ATTORNEY
  
  
       We, the undersigned officers and directors of GelTex Pharmaceuticals, Inc.
  hereby severally constitute and appoint Mark Skaletsky and Peter Wirth, and each
  of them singly, our true and lawful attorneys-in-fact, with full power to them
  in any and all capacities, to sign any and all amendments to this Registration
  Statement on Form S-8 including any post-effective amendments thereto, and to
  file the same, with exhibits thereto and other documents in connection
  therewith, with the Securities and Exchange Commission, hereby ratifying and
  confirming all that each of said attorneys-in-fact may do or cause to be done by
  virtue hereof.
  
       Pursuant to the requirements of the Securities Act of 1933, this
  Registration Statement has been signed below by the following persons in the
  capacities and on the dates indicated:
  
           SIGNATURE            TITLE                               DATE
           ---------            -----                               ----
  
  
  /s/ Mark Skaletsky            President, Chief Executive          July 19, 1996
  - --------------------------    Officer and Treasurer               
  Mark Skaletsky                (Principal Executive                
                                Officer, Principal Financial Officer
                                and Principal Accounting Officer)   
                                                                    
  
  /s/ Robert J. Carpenter       Chairman of the Board               July 19, 1996
  - --------------------------    and Director
  Robert J. Carpenter           
  
  
  /s/ Ernest Parizeau           Director                            July 19, 1996
  - --------------------------
  Ernest Parizeau
  
                                       - 20 -
  
  <PAGE>   21
  
  
  
  
           SIGNATURE             TITLE                     DATE
           ---------             -----                     ----
  
  
  /s/ Barbara A. Piette          Director                   July 19, 1996
  - --------------------------
  Barbara A. Piette
  
  
  /s/ James Tananbaum            Director                   July 19, 1996
  - --------------------------
  James Tananbaum
  
  
  /s/ Henri A. Termeer           Director                   July 19, 1996
  - --------------------------
  Henri A. Termeer
  
  
  /s/ Jesse Treu                 Director                   July 19, 1996
  - --------------------------
  Jesse Treu
  
  
  /s/ George Whitesides          Director                   July 19, 1996
  - --------------------------
  George Whitesides
  
                                       - 21 -
  
  <PAGE>   22
  
  <TABLE>
  
                                            EXHIBIT INDEX
                                            -------------
  
  
  <CAPTION>
  Exhibit Number                             Description                            Page Number
  - --------------                             -----------                            -----------
  
      <S>               <C>                                                             <C>
       4.1              Restated Certificate of Incorporation of the Registrant.         *
                        Filed as Exhibit 4.1 to the Company's Registration             
                        Statement on Form S-8 (File No. 333-6779).                     
                                                                                       
       4.2              Amended and Restated By-laws of the Registrant.                  *
                        Filed as Exhibit 3.3 to the Company's Annual Report            
                        on Form 10-K for the fiscal year ended December 31,            
                        1995.                                                          
                                                                                       
       4.3              Rights Agreement dated as of March 1, 1996 between               *
                        the Company and American Stock Transfer & Trust                
                        Company.  Filed as Exhibit 1 to the Company's                  
                        Registration Statement on Form 8-A dated March 1,              
                        1996.                                                          
                                                                                       
       5.1              Opinion of Palmer & Dodge LLP as to the legality of             23
                        the securities registered hereunder.                           
                                                                                       
      23.1              Consent of Ernst & Young LLP, independent auditors.             24
                                                                                       
      23.2              Consent of Palmer & Dodge LLP (contained in                     --
                        Opinion of Palmer & Dodge LLP, filed as Exhibit 5.1            
                        hereto).                                                       
                                                                                       
      24.1              Power of Attorney (set forth on the signature page to           --
                        this Registration Statement).                                  
                                                                                       
      24.2              Certified resolution of the Board of Directors                  25
                        authorizing Power of Attorney.                                 
                                                                                       
      99.1              1992 Equity Incentive Plan, as amended through                  26
                        May 20, 1996.                                                   
  <FN>                                                                                   
  
  - ----------------------------
  
  *  Incorporated herein by reference.
  </TABLE>
  
  
                                       - 22 -
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metadata_filer: {"company-data": {"conformed-name": "GELTEX PHARMACEUTICALS INC", "cik": "0001001425", "assigned-sic": "2834", "irs-number": "043136767", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-08535", "film-number": "96597132"}, "business-address": {"street1": "303 BEAR HILL RD", "city": "WALTHAM", "state": "MA", "zip": "02154", "phone": "6172905888"}, "mail-address": {"street1": "303 BEAR HILL RD", "city": "WALTHAM", "state": "MA", "zip": "02154"}}
text: 1
        As filed with the Securities and Exchange Commission on July 22, 1996
  
                                                   REGISTRATION NO. 333-
                                                                        ------
  
                         SECURITIES AND EXCHANGE COMMISSION
                               Washington, D. C. 20549
  
                             ---------------------------
  
                                      FORM S-8
  
                            REGISTRATION STATEMENT UNDER
                             THE SECURITIES ACT OF 1933
  
                             ---------------------------
  
                            GELTEX PHARMACEUTICALS, INC.
               (Exact name of registrant as specified in its charter)
  DELAWARE                                       04-3136767
  (State or other jurisdiction of incorporation)   (I.R.S. Employer Identification No.)
  303 BEAR HILL ROAD, WALTHAM, MASSACHUSETTS 02154 (617) 290-5888
     (Address and telephone number of registrant's principal executive offices)
  
                             ---------------------------
  
                             1992 EQUITY INCENTIVE PLAN
                              (Full Title of the Plan)
  
                MARK SKALETSKY, PRESIDENT AND CHIEF EXECUTIVE OFFICER
                            GelTex Pharmaceuticals, Inc.
                                 303 Bear Hill Road
                            Waltham, Massachusetts 02154
                                   (617) 290-5888
              (Name, address and telephone number of agent for service)
  
                                   with copies to:
  
                                PETER WIRTH, ESQUIRE
                                 Palmer & Dodge LLP
                                  One Beacon Street
                             Boston, Massachusetts 02108
                                   (617) 573-0100
  
                             ---------------------------
  
                                           CALCULATION OF REGISTRATION FEE
  - -----------------------------------------------------------------------------------------------------------------------------------
  Title of each class of securities to     Amount to be              Proposed             Proposed maximum          Amount of
            be registered                   registered           maximum offering        aggregate offering      registration fee
                                                                  price per share              price
  - -----------------------------------------------------------------------------------------------------------------------------------
  Common Stock, $0.01 par value        778,251 shares (1)                  (2)           $ 3,848,731.94(3)          $1,324.00
  - -----------------------------------------------------------------------------------------------------------------------------------
  Common Stock, $0.01 par value        927,334 shares                $14.00(4)           $12,982,676.00(4)          $4,477.00
  - -----------------------------------------------------------------------------------------------------------------------------------
  (1)      Shares subject to currently outstanding options.
  (2)      The price per share at which currently outstanding options may be exercised ranges from $.125 to $24.25 per share.
  (3)      Computed in accordance with Rule 457(h)(1) based on the price per share at which currently outstanding options may be
           exercised.
  (4)      Estimated solely for the purpose of determining the registration fee and computed pursuant to Rule 457(h) based upon the
           average of the high and low sale prices on July 17, 1996 as reported by the Nasdaq National Market System.
  Page 1 of 32
                          Exhibit Index Appears at Page 22
  2
  
  PROSPECTUS
  
                                   490,300 Shares
  
                            GELTEX PHARMACEUTICALS, INC.
  
                                    Common Stock
  
                               ----------------------
  
       This Prospectus relates to the offer and sale (the "Offering") of up to
  490,300 shares (the "Shares") of Common Stock, $.01 par value per share (the
  "Common Stock"), of GelTex Pharmaceuticals, Inc. ("GelTex" or the "Company").
  The Shares may be offered by certain stockholders of the Company identified
  herein and their pledgees, donees, transferees or other successors in interest
  (the "Selling Stockholders") from time to time in transactions on the Nasdaq
  National Market System, in privately negotiated transactions, or by a
  combination of such methods of sale, at fixed prices that maybe changed, at
  market prices prevailing at the time of sale, at prices related to such
  prevailing market prices or at negotiated prices. The Selling Stockholders may
  effect such transactions by selling the Shares to or through broker-dealers and
  such broker-dealers may receive compensation in the form of discounts,
  concessions or commissions form the Selling Stockholders or the purchasers of
  the Shares for whom such broker-dealer may act as agent or to whom they sell as
  principal or both (which compensation to a particular broker-dealer might be in
  excess of customary commissions). See "Selling Stockholders" and "Plan of
  Distribution."
  
       None of the proceeds from the sale of the Shares by the Selling
  Stockholders will be received by the Company. The Company will bear certain
  expenses (other than fees and expenses, if any, of more than one counsel or
  advisors to the Selling Stockholders) in connection with the registration and
  sale of the Shares being offered by the Selling Stockholders.
  
       The Common Stock is quoted on the Nasdaq National Market under the symbol
  "GELX." On July 18, 1996, the last sale price of the Company's Common Stock was
  $14.50 per share. See "Price Range of Common Stock."
  
                               ----------------------
  
              THE COMMON STOCK OFFERED HEREBY INVOLVES A HIGH DEGREE OF
          RISK. SEE "RISK FACTORS" BEGINNING ON PAGE 6 OF THIS PROSPECTUS.
  
                               ----------------------
  
  THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
  EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION NOR HAS THE SECURITIES
  AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION PASSED UPON THE
  ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A
  CRIMINAL OFFENSE.
  
  NO PERSON IS AUTHORIZED IN CONNECTION WITH ANY OFFERING MADE HEREBY TO GIVE ANY
  INFORMATION OR TO MAKE ANY REPRESENTATIONS OTHER THAN AS CONTAINED IN THIS
  PROSPECTUS, AND, IF GIVEN OR MADE, SUCH INFORMATION OR REPRESENTATIONS MUST NOT
  BE RELIED UPON AS HAVING BEEN AUTHORIZED BY THE COMPANY. THIS PROSPECTUS IS NOT
  AN OFFER TO SELL, OR A SOLICITATION OF AN OFFER TO BUY, BY PERSON IN ANY
  JURISDICTION IN WHICH IT IS UNLAWFUL FOR SUCH PERSON TO MAKE SUCH AN OFFER OR
  SOLICITATION. NEITHER THE DELIVERY OF THIS PROSPECTUS NOR ANY SALES MADE
  HEREUNDER SHALL UNDER ANY CIRCUMSTANCES CREATE ANY IMPLICATION THAT THE
  INFORMATION CONTAINED HEREIN IS CORRECT AS OF ANY TIME SUBSEQUENT TO THE DATE
  HEREOF.
                    The date of this Prospectus is July 19, 1996.
  3
  
                                AVAILABLE INFORMATION
  
       The Company has filed with the Securities and Exchange Commission (the
  "Commission") a Registration Statement under the Securities Act of 1933, as
  amended, with respect to the shares of Common Stock offered hereby. This
  Prospectus does not contain all of the information set forth in the Registration
  Statement and the exhibits and schedules thereto. For further information with
  respect to the Company and the Common Stock offered hereby, reference is made to
  such Registration Statement and the exhibits and schedules thereto. Statements
  made in this Prospectus as to the contents of any contract, agreement or other
  document filed as an exhibit to the Registration Statement are not necessarily
  complete, and in each such instance reference is made to the copy of such
  document filed as an exhibit to the Registration Statement, each such statement
  being deemed qualified in its entirety by such reference. A copy of the
  Registration Statement may be inspected without charge at the offices of the
  Commission, 450 Fifth Street, N.W., Washington, D.C. 20549, and copies of all or
  any part thereof may be obtained from the Commission upon the payment of certain
  fees prescribed by the Commission.
  
                               ----------------------
  
                  INCORPORATION OF CERTAIN INFORMATION BY REFERENCE
  
       The following documents filed with the Securities and Exchange Commission
  (the "Commission") are incorporated herein by reference:
  
       (a) The Registrant's Annual Report on Form 10-K for the fiscal year ended
  December 31, 1995 (File No. 0-26872) filed with the Commission on March 29,
  1996.
  
       (b) The Registrant's Quarterly Report on Form 10-Q for the fiscal quarter
  ended March 31, 1996 (File No. 0-26872) filed with the Commission on May 13,
  1996.
  
       (c) The Registrant's Current Reports on Form 8-K dated March 1, 1996 and
  June 26, 1996 (File No. 0-26872) filed with the Commission on March 4, 1996 and
  June 28, 1996, respectively.
  
       (d) The Registrant's report on Form 10-C dated May 14, 1996 (File No.
  0-26872) filed with the Commission on May 17, 1996.
  
       (e) All other reports of the Registrant filed pursuant to Section 13(a) or
  15(d) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"),
  since the end of the fiscal year covered by the annual report referred to in (a)
  above.
  
       (f) The description of the Registrant's Common Stock contained in its
  Registration Statement on Form 8-A (File No. 0-26872) filed with the Commission
  on September 26, 1995, as amended on October 12, 1995, including any amendment
  or report filed hereafter for the purpose of updating such description.
  
       All documents filed after the date of this Registration Statement by the
  Registrant pursuant to Section 13(a), 13(d), 14 and 15(d) of the Exchange Act
  and prior to the filing of a post-effective amendment that indicates that all
  shares of Common Stock offered hereunder have been sold or which deregisters all
  shares of Common Stock remaining unsold shall be deemed to be incorporated by
  reference herein and to be a part hereof from the date of the filing of such
  reports and documents.
  
       The Company will furnish without charge to each person, including
  beneficial owners, to whom this Prospectus is delivered, on written or oral
  request, copies of the documents incorporated in this Prospectus by reference,
  other than exhibits to such documents. Requests should be directed to Sarah P.
  Cecil, Attorney, GelTex Pharmaceuticals, Inc., 303 Bear Hill Road, Waltham,
  Massachusetts 02154 (telephone: 617-290-5888).
  
                                        - 3 -
  4
  
                                  TABLE OF CONTENTS
  
                                                                     Page
                                                                     ----
  
  The Company...................................................        5
  
  Risk Factors..................................................        6
  
  Selling Stockholders..........................................       12
  
  Plan of Distribution..........................................       15
  
  Legal Matters.................................................       15
  
  Experts.......................................................       15
  
                                        - 4 -
  5
  
                                     THE COMPANY
  
          GelTex Pharmaceuticals, Inc. ("GelTex" or the "Company") is developing
  non-absorbed, polymer-based pharmaceuticals that selectively bind to and
  eliminate target substances from the intestinal tract. In March 1996, GelTex
  successfully completed a Phase IIa clinical trial of CholestaGel[Registered
  Trademark] non-absorbed cholesterol reducer, for the treatment of elevated
  cholesterol levels. This double-blind, placebo-controlled, dose ranging trial
  demonstrated a clinically and statistically significant reduction in LDL
  cholesterol levels in patients with hyperchlosteralemia (elevated cholesterol).
  The preliminary results indicate that CholestaGel may be four to five times
  more potent than cholestyramine, the most widely prescribed non-absorbed
  cholesterol-reducing drug, and appears to be well tolerated. The Company
  initiated a Phase IIb clinical trial in subjects with elevated LDL cholesterol
  in June 1996, and additional Phase II trials investigating dose scheduling and
  combination therapies are planned. Also, the Company completed, in April 1996,
  a Phase IIb clinical trial of RenaGel[Registered Trademark] phosphate binder,
  for the control of elevated phosphorus levels in chronic kidney failure
  patients. The Company initiated Phase III clinical trials for RenaGel in June
  1996. The Company is also conducting research to develop non-absorbed,
  polymer-based pharmaceuticals for the treatment of certain infections of the
  intestinal tract, such as those caused by Cryptosporidium parvum and human
  rotavirus.
  
       GelTex's pharmaceuticals act in the intestinal tract without absorption
  into the bloodstream, thereby minimizing the potential for adverse effects. The
  Company's product development approach represents an advance in the use of
  polymer hydrogels as pharmaceuticals. The Company's technology combines an
  understanding of chemical interactions necessary for molecular recognition with
  the ability to design and synthesize polymer hydrogels. The Company's technology
  enables it to combine commercially available monomers that have distinct
  structural qualities to create proprietary, non-absorbed polymers that
  selectively bind target molecules. The Company designs its polymers to carry a
  high density of selective binding sites for the targeted molecules, making them
  potent at low dosage levels and permitting oral administration in a convenient
  capsule form.
  
       GelTex is developing CholestaGel, an orally administered, non-absorbed
  hydrogel intended to reduce elevated LDL cholesterol levels in patients with
  hypercholesterolemia. The Company believes that the structural design of
  CholestaGel represents a significant advance over existing bile acid
  sequestrants in that its high density of bile acid binding sites makes it more
  potent at lower doses than currently marketed agents. The Company expects
  CholestaGel to address the need for a non-absorbed cholesterol-reducing drug
  that is safe and well tolerated in long term use, effective at low doses and
  available in a convenient capsule form.
  
       GelTex is developing RenaGel, an orally administered, non-absorbed hydrogel
  intended to control elevated blood phosphorus levels in patients with chronic
  kidney failure. RenaGel is designed to provide significant advantages over
  currently available calcium- and aluminum-based phosphate binders. RenaGel binds
  dietary phosphate without the use of either calcium or aluminum and, therefore,
  will not cause dangerous elevated blood calcium levels or aluminum toxicities.
  The Company intends to supply RenaGel in a convenient capsule form that is more
  palatable than the chalky chewable and acidic uncoated tablet forms of currently
  available phosphate binders. [In a Phase IIa clinical trial completed in August
  1995, designed to show equivalent potency to currently available calcium-based
  phosphate binders, RenaGel demonstrated such potency and was shown to be safe
  and well tolerated by dialysis patients. The Phase IIb clinical trial completed
  in April 1996 demonstrated that RenaGel significantly decreased serum phosphorus
  without increasing serum calcium.] In December 1994, GelTex granted Chugai
  Pharmaceutical Co., Ltd. an exclusive license to develop and commercialize
  RenaGel in Japan and other Pacific Rim countries.
  
       The Company's infectious disease program is directed toward developing
  non-absorbed polymers that bind, inactivate and remove specific pathogens from
  the intestinal tract. GelTex is initially focusing on two pathogens that cause
  debilitating diarrhea and for which no drug treatment currently exists:
  Cryptosporidium parvum, a parasite which causes chronic diarrhea in
  immunocompromised patients; and human rotavirus, which causes diarrhea in
  children.
  
       The Company believes its enabling technology is applicable to a broad range
  of diseases and conditions treatable through the intestinal tract. Specifically,
  the Company believes that conditions such as ulcers and inflammatory bowel
  diseases, including Crohn's disease and ulcerative colitis, could be treated
  with non-absorbed, polymer-based products developed using the Company's
  technology.
  
       GelTex was incorporated in Delaware in November 1991. The Company's
  executive offices are located at 303 Bear Hill Road, Waltham, Massachusetts
  02154 and its telephone number is (617) 290-5888.
  
       CholestaGel[Registered Trademark] and RenaGel[Registered Trademark] are a
  registered trademarks of the Company.
  
                                        - 5 -
  6
  
                                    RISK FACTORS
  
       An investment in the shares of Common Stock offered hereby involves a high
  degree of risk. The following factors, in addition to the other information in
  this Prospectus, should be carefully considered in evaluating the Company and
  its business before purchasing the shares of Common Stock offered hereby.
  
  EARLY STAGE OF DEVELOPMENT; NO PRODUCT SALES TO DATE
  
       GelTex is a development stage company, and there can be no assurance that
  its approach to the development of non-absorbed, polymer-based pharmaceuticals
  will be successful. The Company's potential products are in various stages of
  research or development and will require substantial additional development,
  preclinical and clinical testing and investment prior to commercialization.
  There can be no assurance that the Company's research and development efforts
  will be successful or that any of its potential products will be demonstrated to
  be safe, efficacious or marketable. The Company's revenues to date have
  consisted primarily of licensing fees and research revenues from corporate
  partners in connection with two development and marketing agreements. No
  revenues have been generated from product sales, and products resulting from the
  Company's research and development efforts, if any, are not expected to be
  commercially available for a number of years. No assurance can be given that the
  Company's product development efforts will be successful, that required
  regulatory approvals can be obtained, that its products can be manufactured at
  acceptable cost and with appropriate quality or that any approved products can
  be successfully marketed.
  
  CONTINUING OPERATING LOSSES
  
       As of March 31, 1996, the Company had accumulated net losses of
  approximately $13.1 million. The continuing development of the Company's
  potential products will require the commitment of substantial resources to
  conduct research, preclinical studies and clinical trials and to establish
  effective commercial manufacturing processes. The Company expects to incur
  substantial operating losses for at least the next several years as it continues
  to develop its potential products. The amount of net losses and the time
  required to reach sustained profitability are highly uncertain. To achieve
  sustained profitable operations, the Company, alone or with corporate partners,
  must successfully develop, manufacture and market its products. No assurance can
  be given that the Company will be able to achieve or sustain profitability.
  
  FUTURE CAPITAL NEEDS; UNCERTAINTY OF ADDITIONAL FUNDING
  
       Since inception, the Company has funded its operations primarily through
  the issuance of equity securities. The Company anticipates that it will need to
  raise substantial additional funds for research, development and other expenses,
  through equity or debt financings, research and development financings,
  collaborative relationships or otherwise, prior to the commercialization of any
  of its products. There can be no assurance that any such additional funding will
  be available to the Company or, if available, that it will be on reasonable
  terms. Any such additional financing may result in dilution to existing
  stockholders. If adequate funds are not available, the Company may be required
  to significantly curtail its research and development programs, including
  clinical trials, or enter into arrangements that may require the Company to
  relinquish certain material rights to its products on terms that it might
  otherwise find unacceptable.
  
  UNCERTAINTY ASSOCIATED WITH PRECLINICAL AND CLINICAL TESTING
  
       Before obtaining regulatory approvals for the commercial sale of any of its
  potential products, the products will be subjected to extensive preclinical and
  clinical testing to demonstrate their safety and efficacy in humans. To date,
  the Company has tested CholestaGel and RenaGel in limited numbers of subjects in
  Phase I and Phase II clinical trials. The results of initial preclinical and
  clinical testing of these products under development by the Company are not
  necessarily predictive of results that will be obtained from subsequent or more
  extensive preclinical and clinical testing. Furthermore, there can be no
  assurance that clinical trials of products under development will demonstrate
  the safety and efficacy of such products at all or to the extent necessary to
  obtain regulatory approvals. Companies in the biotechnology industry have
  suffered significant setbacks in advanced clinical trials, even after
  
                                        - 6 -
  7
  
  promising results in earlier trials. The failure to adequately demonstrate the
  safety and efficacy of a therapeutic product under development could delay or
  prevent regulatory approval of the product and would have a material adverse
  effect on the Company.
  
       The rate of completion of clinical trials is dependent upon, among other
  factors, the enrollment of patients. Patient accrual is a function of many
  factors, including the size of the patient population, the proximity of patients
  to clinical sites, the eligibility criteria for the study and the existence of
  competitive clinical trials. Delays in planned patient enrollment in the
  Company's current trials or future clinical trials may result in increased
  costs, program delays or both, which could have a material adverse effect on the
  Company. There can be no assurance that if clinical trials are completed the
  Company will be able to submit a New Drug Application ("NDA") as scheduled or
  that any such application will be reviewed and approved by the United States
  Food and Drug Administration ("FDA") in a timely manner, or at all.
  
  DEPENDENCE ON CORPORATE ALLIANCES
  
       The Company expects to develop and market its potential products through
  alliances with corporate partners. The Company is currently engaged in one such
  collaboration to develop and commercialize RenaGel phosphate binder in Japan and
  other Pacific Rim countries. The Company is relying upon its partner to conduct
  clinical trials, obtain regulatory approval for the sale of the products in the
  territory covered by the agreement and manufacture and market the products in
  the territory. There can be no assurance that its partner will devote the
  resources necessary to complete development of and commence marketing for the
  products in the territory. The agreement is subject to termination without cause
  on short notice under certain circumstances and there is no assurance that in
  the future the Company's partner will not exercise its termination rights.
  
       The Company expects to enter into other development and marketing
  agreements in other territories for its potential products, and in connection
  with such agreements will rely upon corporate partners to conduct clinical
  trials, obtain regulatory approval for and manufacture and market its potential
  products. There can be no assurance that the Company will be able to establish
  agreements for the commercialization of RenaGel in other parts of the world or
  for the commercialization of the Company's other products. The termination of
  its existing agreements and the failure to secure additional development and
  marketing agreements with other corporate partners would have a material adverse
  effect on the Company's operations.
  
  DEPENDENCE ON SINGLE SOURCE OF SUPPLY; NO SUPPLY AGREEMENT
  
       The Company uses a single supplier to provide a certain raw material
  necessary for the manufacture of CholestaGel and RenaGel. The supplier has a
  composition of matter patent covering the material, and the Company believes
  that currently there are no alternative suppliers of this material. The Company
  does not have a long term, fixed price supply agreement for this raw material
  but rather obtains the raw material by issuing purchase orders to the supplier
  on an as needed basis. To date, the Company has not experienced any difficulty
  in obtaining adequate supplies of the raw material. However, no assurance can be
  given that the raw material will remain available to the Company or to its
  corporate partners in commercial quantities at acceptable costs. Should the
  Company or its corporate partners be unable to obtain an adequate supply of the
  material at commercially reasonable rates, the operations of the Company would
  be adversely affected.
  
  NO ASSURANCE OF FDA APPROVAL; COMPREHENSIVE GOVERNMENT REGULATION
  
       The Company's research, development and clinical programs, as well as the
  operations of its third party manufacturers and the marketing operations of its
  corporate partners, are subject to extensive regulation by numerous governmental
  authorities in the United States and other countries. The Company's potential
  products require governmental approvals for commercialization, which have not
  yet been obtained and are not expected to be obtained for several years. The
  regulatory process, which includes preclinical, clinical and, in certain
  instances, post-marketing testing to establish safety and efficacy, can take
  many years and require the expenditure of substantial resources. The Company has
  had only limited experience in conducting preclinical testing and human clinical
  trials and obtaining FDA and other regulatory approvals. Data obtained from
  preclinical and clinical activities are susceptible to varying interpretations,
  which could delay, limit or prevent regulatory approval. In addition, delays or
  rejection may be encountered based upon changes in, or additions to, regulatory
  policies for drug approval during
  
                                        - 7 -
  8
  
  the period of product development and regulatory review. Delays in obtaining
  such approvals could adversely affect the marketing of products developed by the
  Company and the Company's ability to generate commercial product revenues. There
  can be no assurance that requisite regulatory approvals will be obtained within
  a reasonable period of time, if at all. Moreover, if regulatory approval of a
  product is granted, such approval may impose limitations on the indicated uses
  for which such product may be marketed. Further, even if such regulatory
  approval is obtained, a marketed product, its manufacturer and its manufacturing
  facilities are subject to continual review and periodic inspections, and later
  discovery of previously unknown problems with a product, manufacturer or
  facility may result in restrictions on such product or manufacturer, including
  withdrawal of the product from the market. Failure to comply with the applicable
  regulatory requirements can, among other things, result in fines, suspensions of
  regulatory approvals, product recalls, operating restrictions and criminal
  prosecution. The Company is also subject to numerous environmental, health and
  workplace safety laws and regulations, including those governing laboratory
  procedures and the handling of biohazardous materials. Any violation of, and
  cost of compliance with, these laws and regulations could adversely affect the
  Company's operations.
  
  TECHNOLOGICAL CHANGE; COMPETITION
  
       The biotechnology and pharmaceutical industries are subject to rapid and
  significant technological change. Competitors of GelTex in the United States and
  abroad are numerous and include, among others, pharmaceutical and biotechnology
  companies, universities and other research institutions. The Company's success
  depends upon developing and maintaining a competitive position in the
  development of products and technologies in its areas of focus. There can be no
  assurance that the Company's competitors will not succeed in developing
  technologies and products that are more effective than any which are being
  developed by the Company or which would render the Company's technology and
  products obsolete or noncompetitive. Many of these competitors have
  substantially greater financial and technical resources and production and
  marketing capabilities than the Company, and certain of these competitors may
  compete with the Company in establishing development and marketing agreements
  with pharmaceutical companies. In addition, many of the Company's competitors
  have greater experience than the Company in conducting preclinical testing and
  human clinical trials and obtaining FDA and other regulatory approvals. The
  Company's competitors may succeed in obtaining FDA approval for products more
  rapidly than the Company.
  
       The pharmaceutical industry is intensely competitive. Many companies,
  including biotechnology, chemical and pharmaceutical companies, are actively
  engaged in activities similar to those of the Company, including research and
  development of products for hypercholesterolemia, hyperphosphatemia,
  cryptosporidiosis and human rotavirus infection. In the cholesterol-reduction
  field, products are currently available that address some of the needs of the
  market. These products include other bile acid sequestrants, HMG-CoA reductase
  inhibitors, fibric acid derivatives and niacin. In 1994, sales of HMG-CoA
  reductase inhibitors represented approximately 68% of the market for
  cholesterol-reducing drugs sold in the United States. Worldwide sales of the
  three leading HMG-CoA reductase inhibitors each exceeded $1 billion in 1995.
  Several phosphate binders are also currently available. A prescription calcium
  acetate preparation is currently the only product approved in the United States
  for the control of elevated phosphorus levels in patients with chronic kidney
  failure. Other products used as phosphate binders include over-the-counter
  calcium- and aluminum-based antacids and dietary calcium supplements. While the
  Company believes that its products will offer significant advantages over
  available agents, currently marketed products often have a significant
  competitive advantage over new entrants. There can be no assurance that the
  Company's products under development will be able to compete successfully with
  existing therapies or with products under development by other companies,
  universities and other institutions.
  
  DEPENDENCE ON PATENTS AND PROPRIETARY TECHNOLOGY
  
       The biotechnology and pharmaceutical industries place considerable
  importance on obtaining patent and trade secret protection for new technologies,
  products and processes. The Company's success will depend, in part, on its
  ability to obtain patent protection for its products and manufacturing
  processes, preserve its trade secrets and operate without infringing the
  proprietary rights of third parties. The Company has ongoing research efforts
  and expects to seek additional patents covering this research in the future.
  There can be no assurance of its success or timeliness in obtaining any patents,
  or of the breadth or degree of protection that any such patents will afford the
  Company. The patent position of biotechnology and pharmaceutical products is
  often highly uncertain and usually involves complex legal and factual questions.
  There can be no assurance that patent applications relating to the
  
                                        - 8 -
  9
  
  Company's potential products or technology will result in patents being issued
  or that any current or future patents will afford adequate protection to the
  Company or not be challenged, invalidated or infringed. Furthermore, there can
  be no assurance that others will not independently develop similar products and
  processes, duplicate any of the Company's products or, if patents are issued to
  the Company, design around such patents. In addition, the Company could incur
  substantial costs in defending itself in suits brought against it or in suits in
  which the Company may assert its patents against others. If the outcome of any
  such litigation is unfavorable to the Company, the Company's business could be
  adversely affected. To determine the priority of inventions, the Company may
  also have to participate in interference proceedings declared by the United
  States Patent and Trademark Office, which could result in substantial cost to
  the Company.
  
       In addition, the Company may be required to obtain licenses to patents or
  other proprietary rights of third parties. No assurance can be given that any
  licenses required under any such patents or proprietary rights would be made
  available on terms acceptable to the Company, if at all. If the Company does not
  obtain such licenses, it could encounter delays in product market introductions
  while it attempts to design around such patents or other rights, or it may be
  unable to develop, manufacture or sell such products.
  
       The Company also seeks to protect its proprietary technology, including
  technology which may not be patented nor patentable, in part by confidentiality
  agreements and, if applicable, inventors' rights agreement with its
  collaborators, advisors, employees and consultants. There can be no assurance
  that these agreements will not be breached, that the Company will have adequate
  remedies for any breach or that the Company's trade secrets will not otherwise
  be disclosed to, or discovered by, competitors. There can be no assurance that
  such persons or institutions will not assert rights to intellectual property
  arising out of such research.
  
  DEPENDENCE ON OTHERS FOR MANUFACTURING; PROCESS DEVELOPMENT RISKS
  
       The Company has chosen not to develop the capability to manufacture its
  potential products in clinical or commercial quantities and, therefore, must
  rely upon third party manufacturers for the production of its compounds for
  preclinical and clinical trial purposes. The Company expects to rely upon third
  party manufacturers for commercial production. In the event that the Company is
  unable to obtain contract manufacturing on commercially reasonable terms, it may
  not be able to commercialize its potential products as planned. The Company's
  dependence on third parties for the manufacture of its potential products may
  adversely affect the Company's profit margins, its ability to develop and
  manufacture products on a timely and competitive basis, the progress of clinical
  trials, the timing of market introductions and subsequent sales of such
  products.
  
       The Company has not yet established effective processes for the manufacture
  of commercial quantities of its potential products. Significant process
  development work will be required to establish such processes. There can be no
  assurance that such process development work will be successful or that the
  Company will obtain rights to use, or license its corporate partners to use,
  such commercial processes.
  
  ABSENCE OF SALES AND MARKETING EXPERIENCE
  
       The Company has no experience in sales, marketing or distribution. The
  Company plans to establish marketing arrangements with pharmaceutical companies
  with large distribution capabilities in order to market its products. As a
  result, sales of the Company's products will depend upon the efforts of third
  parties and there can be no assurance that such efforts will be successful.
  
  PRODUCT LIABILITY AND LIMITED INSURANCE
  
       The Company's business exposes it to potential product liability claims,
  which are inherent in the testing, manufacturing, marketing and sale of human
  therapeutics. The use of the Company's product candidates in clinical trials
  also exposes the Company to product liability claims and possible adverse
  publicity. These risks increase with respect to the Company's product
  candidates, if any, that receive regulatory approval for commercialization. The
  Company currently has limited product liability insurance coverage for the
  clinical research use of its product candidates. The Company does not have
  product liability coverage for the commercial sale of its products but intends
  to obtain such coverage if and when its products are commercialized. However,
  there can be no assurance
  
                                        - 9 -
  10
  
  that the Company will be able to obtain additional insurance coverage on
  acceptable terms, if at all, or that a product liability claim would not
  materially adversely affect the business of the Company.
  
  DEPENDENCE ON REIMBURSEMENT
  
       In both domestic and foreign markets, the ability of the Company to
  commercialize its products will depend, in part, on the availability of
  reimbursement from third-party payors, such as government health administration
  authorities, private health insurers and other organizations. Third-party payors
  are increasingly challenging the price and cost effectiveness of medical
  products. There can be no assurance that the Company's potential products will
  be considered cost effective. If adequate coverage and reimbursement levels are
  not provided by the government and third-party payors for uses of the Company's
  therapeutic products, the market acceptance of these products would be adversely
  affected. This is particularly true with the respect to the Company's RenaGel
  product, which the Company anticipates will compete with certain low priced
  over-the-counter products.
  
  DEPENDENCE UPON KEY PERSONNEL
  
       The Company is highly dependent on the members of its management and
  scientific staff, the loss of one or more of whom could have a material adverse
  effect on the Company. In addition, the Company believes that its future success
  will depend in large part upon its ability to attract and retain highly skilled
  scientific and managerial personnel, particularly as the Company expands its
  activities in clinical trials and the regulatory approval process. The Company
  faces significant competition for such personnel from other companies, research
  and academic institutions, government entities and other organizations. There
  can be no assurance that the Company will be successful in hiring or retaining
  the personnel it requires for continued growth. The failure to hire and retain
  such personnel could materially and adversely affect the Company.
  
  ABSENCE OF DIVIDENDS
  
       The Company has never paid dividends and does not intend to pay any cash
  dividends in the foreseeable future.
  
  POTENTIAL VOLATILITY OF STOCK PRICE
  
       The market price of the shares of Common Stock, like that of the common
  stock of many other development stage biotechnology companies, may be highly
  volatile. Factors such as announcements of technological innovations or new
  commercial products by the Company or its competitors, disclosure of results of
  clinical testing or regulatory proceedings, governmental regulation and
  approvals, developments in patent or other proprietary rights, public concern as
  to the safety of products developed by the Company and general market conditions
  may have a significant effect on the market price of the Common Stock. In
  addition, the stock market has experienced extreme price and volume
  fluctuations. This volatility has significantly affected the market prices of
  securities of many biotechnology and pharmaceutical companies for reasons
  frequently unrelated to or disproportionate to the operating performance of the
  specific companies. These broad market fluctuations may adversely affect the
  market price of the Company's Common Stock.
  
  CONTROL BY EXISTING STOCKHOLDERS
  
       As of June 30, 1996, the Company's directors, executive officers and 5%
  stockholders and certain of their affiliates beneficially own approximately 49%
  of the outstanding shares of the Common Stock. Accordingly, they have the
  ability to control the election of the Company's directors and significantly
  influence or control other stockholder actions.
  
  ANTI-TAKEOVER PROVISIONS
  
       The Company's Restated Certificate of Incorporation, and Amended and
  Restated By-laws of the Company contain provisions that could discourage
  potential takeover attempts and prevent stockholders from changing the Company's
  management. The Company's Restated Certificate of Incorporation authorizes the
  Board to issue shares of preferred stock without further action by the
  stockholders. The Company's Restated Certificate of Incorporation
  
                                       - 10 -
  11
  
  also includes provisions (i) classifying the Board of Directors into three
  classes with staggered three-year terms, (ii) prohibiting stockholder action by
  written consent except as otherwise provided by law and (iii) requiring the
  approval of the holders of two-thirds of the Company's capital stock for certain
  transactions. The Company's Bylaws also provide that special meetings of the
  Company's stockholders may be called only by the President or the directors and
  require advance notice of business to be brought by a stockholder before the
  annual meeting. The Company has also adopted a stockholders rights plan. The
  stockholders rights plan together with the aforementioned charter and by-law
  provisions may discourage certain types of transactions involving an actual or
  potential change in control of the Company, including transactions in which the
  stockholders might otherwise receive a premium for their shares over then
  current prices, and may limit the ability of the stockholders to approve
  transactions they may deem to be in their best interest. In addition, the Board
  of Directors has the authority, without action by the stockholders, to fix the
  rights and preferences of and to issue shares of preferred stock which also may
  have the effect of delaying or preventing a change in control of the Company.
  
                                       - 11 -
  12
  
                                SELLING STOCKHOLDERS
  
       The Shares being offered hereby were acquired by the persons listed in the
  table below pursuant to stock option exercises under the Company's 1992 Equity
  Incentive Plan. The table below sets forth the number of Shares held as of July
  10, 1996 by affiliates and non-affiliates of the Company. All of the Shares are
  being registered for resale pursuant to a Registration Statement on Form S-8, of
  which this Prospectus is a part. Selling Stockholders may offer the Shares for
  resale from time to time. See "Plan of Distribution."
  Shares Owned Prior                                      Shares Owned After
                                           to Offering(1)                                           Offering(1)
                                        --------------------        Number of Shares             ------------------
  Selling Stockholder                   Number       Percent          Being Offered              Number    Percent
  - -------------------                   ------       -------        ----------------             ------    -------
  Peter M. Ahern                           500             *               500                       --         --
  Robert C. Blanks                      14,000 (2)         *            14,000 (2)                   --         --
  Suanne Bodenrader                      1,000 (3)         *             1,000 (3)                   --         --
  Charles H. Boyd                        3,000 (4)         *             3,000 (4)                   --         --
  Steven K. Burke                       50,000 (5)         *            50,000 (5)                   --         --
  Xi Chen                                3,000 (6)         *             3,000 (6)                   --         --
  Lisa A. D'Attanasio                    3,000 (7)         *             3,000 (7)                   --         --
  Eileen M. Doyle                        3,000 (8)         *             3,000 (8)                   --         --
  Leslie Fay-Warris                      1,516             *             1,516                       --         --
  Venkata Garigpati                     15,000 (9)         *            15,000 (9)                   --         --
  Dennis I. Goldberg                    75,000 (10)        *            75,000 (10)                  --         --
  Alan Hofmann                           7,000             *             7,000                       --         --
  Stephen R. Holmes-Farley              22,400 (11)        *            22,400 (11)                  --         --
  Cynthia R. Maloney                       300             *               300                       --         --
  W. Harry Mandeville                   80,000 (12)        *            40,000 (12)              40,000          *
  Salvatore Marchese                     7,500             *             7,500                       --         --
  Karen L. Miller                        3,000 (13)        *             3,000 (13)                  --         --
  Robert J. Nicolosi                     5,000             *             5,000                       --         --
  Kenneth A. Norton                     10,850 (14)        *            10,850 (14)                  --         --
  John S. Peterson                      29,000 (15)        *            29,000 (15)                  --         --
  Mary C. Pitruzello                     4,000 (16)        *             4,000 (16)                  --         --
  David P. Rosenbaum                    25,000 (17)        *            25,000 (17)                  --         --
  Robert J. Sacchiero                    1,600             *             1,600                       --         --
  Ken Setchell                          15,000             *            15,000                       --         --
  Mark Skaletsky                        80,000 (18)        *            80,000 (18)                  --         --
  Edwin E. Sopp                          2,300 (19)        *             2,300 (19)                  --         --
  Joseph E. Tyler                       30,000 (20)        *            30,000 (20)                  --         --
  James L. Ward                          3,000 (21)        *             3,000 (21)                  --         --
  Amy K. Wilson                         25,000 (22)        *            25,000 (22)                  --         --
  Leslie A. Wyche                          834 (23)        *               834 (23)                  --         --
  Yevgeniy Zhorov                        9,500 (24)        *             9,500 (24)                  --         --
  - --------------------
  *  Indicates less than 1%
  
  (1)  Unless otherwise indicated in these footnotes, each Selling Stockholder has
  sole voting and investment power with respect to the shares listed in the table.
  
  (2)  Includes 7,917 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (3)  Includes 450 Shares subject to a right of repurchase granted to the 
  Company, which will terminate as such Shares vest.
  
  (4)  Includes 1,950 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  - 12 -
  13
  
  (5)  Includes 32,500 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (6)  Includes 1,700 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (7)  Includes 2,050 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (8)  Includes 1,550 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (9)  Includes 7,500 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (10)  Includes 37,500 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (11)  Includes 5,917 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (12)  Includes 18,750 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (13)  Includes 1,101 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (14)  Includes 6,850 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (15)  Includes 17,234 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (16)  Includes 2,217 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (17)  Includes 14,167 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (18)  Includes 10,000 Shares held by Mr. Skaletsky's wife and 6,000 Shares held 
  by his children.
  
  (19)  Includes 1,600 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (20)  Includes 18,334 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (21)  Includes 1,500 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (22)  Includes 12,250 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
  (23)  Includes 767 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
                                       - 13 -
  14
  
  (24)  Includes 6,834 Shares subject to a right of repurchase granted to the
  Company, which will terminate as such Shares vest.
  
       The following Selling Stockholders are officers of the Company: Mark B.
  Skaletsky, President, Chief Financial Officer and Treasurer; Dennis Goldberg,
  Vice President, Product Development and Regulatory Affairs; W. Harry Mandeville,
  Vice President, Chemical Technology; and Joseph Tyler, Vice President,
  Manufacturing.
  
                                       - 14 -
  15
  
                                PLAN OF DISTRIBUTION
  
       The Company has filed with the Commission under the Securities Act of 1933,
  as amended (the "Securities Act"), a Registration Statement on Form S-8, of
  which this Prospectus forms a part, with respect to the resale of the Shares
  from time to time on the Nasdaq National Market System or in
  privately-negotiated transactions.
  
       The Company has been advised that the Selling Stockholders may sell the
  Shares from time to time in transactions on the Nasdaq National Market System,
  in privately negotiated transactions, or by a combination of such methods of
  sale, at fixed prices that maybe changed, at market prices prevailing at the
  time of sale, at prices related to such prevailing market prices or at
  negotiated prices. The Selling Stockholders may effect such transactions by
  selling the Shares to or through broker-dealers and such broker-dealers may
  receive compensation in the form of discounts, concessions or commissions from
  the Selling Stockholders or the purchasers of the Shares for whom such
  broker-dealer may act as agent or to whom they sell as principal or both (which
  compensation to a particular broker-dealer might be in excess of customary
  commissions). The amount of Shares to be sold hereunder by each Selling
  Stockholder and any other person with whom he or she is acting in concert for
  the purpose of selling securities of the Company may not exceed, during any
  three-month period, the amount specified in Rule 144(e) under the Securities
  Act.
  
       The Selling Stockholders and any broker-dealer who acts in connection with
  the sale of Shares hereunder may be deemed to be "underwriters" as that term is
  defined in the Securities Act, and any commissions received by them and profit
  on any resale of the Shares as principal might be deemed to be underwriting
  discounts and commissions under the Securities Act.
  
       The Selling Stockholders may also sell Shares from time to time in
  accordance with Rule 144 or Rule 701 under the Securities Act.
  
                                    LEGAL MATTERS
  
       The validity of the shares of Common Stock offered hereby will be passed
  upon for the Company by Palmer & Dodge LLP, Boston, Massachusetts. Peter Wirth,
  a partner of Palmer & Dodge LLP, is Secretary of the Company.
  
                                       EXPERTS
  
       The financial statements of GelTex Pharmaceuticals, Inc. appearing in
  GelTex Pharmaceuticals, Inc.'s Annual Report (Form 10-K) for the year ended
  December 31, 1995 have been audited by Ernst & Young LLP, independent auditors,
  as set forth in their report thereon included therein and incorporated herein by
  reference. Such financial statements are incorporated herein by reference in
  reliance upon such report given upon the authority of such firm as experts in
  accounting and auditing.
  
                                       - 15 -
  16
  
                                       PART II
                 INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
  
  Item 3.  Incorporation of Documents by Reference.
  - ------------------------------------------------
  
       The following documents filed with the Securities and Exchange Commission
  (the "Commission") are incorporated herein by reference:
  
       (a) The Registrant's Annual Report on Form 10-K for the fiscal year ended
  December 31, 1995 (File No. 0-26872) filed with the Commission on March 29,
  1996.
  
       (b) The Registrant's Quarterly Report on Form 10-Q for the fiscal quarter
  ended March 31, 1996 (File No. 0-26872) filed with the Commission on May 13,
  1996.
  
       (c) The Registrant's Current Reports on Form 8-K dated March 1, 1996 and
  June 26, 1996 (File No. 0-26872) filed with the Commission on March 4, 1996 and
  June 28, 1996, respectively.
  
       (d) The Registrant's report on Form 10-C dated May 14, 1996 (File No.
  0-26872) filed with the Commission on May 17, 1996.
  
       (e) All other reports of the registrant filed pursuant to Section 13(a) or
  15(d) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"),
  since the end of the fiscal year covered by the annual report referred to in (a)
  above.
  
       (f) The description of the Registrant's Common Stock contained in its
  Registration Statement on Form 8-A (File No. 0-26872) filed with the Commission
  on September 26, 1995, as amended on October 12, 1995, including any amendment
  or report filed hereafter for the purpose of updating such description.
  
       All documents filed after the date of this Registration Statement by the
  Registrant pursuant to Section 13(a), 13(d), 14 and 15(d) of the Exchange Act
  and prior to the filing of a post-effective amendment that indicates that all
  shares of Common Stock offered hereunder have been sold or which deregisters all
  shares of Common Stock remaining unsold shall be deemed to be incorporated by
  reference herein and to be a part hereof from the date of the filing of such
  reports and documents.
  
  Item 4.  Description of Securities.
  - ----------------------------------
  
           Not applicable.
  
  Item 5.  Interests of Named Experts and Counsel.
  - -----------------------------------------------
  
       The validity of the Common Stock offered hereby will be passed upon for the
  Registrant by Palmer & Dodge LLP, Boston, Massachusetts. Peter Wirth, a partner
  of Palmer & Dodge LLP, is Secretary of the Registrant.
  
                                       - 16 -
  17
  
  Item 6. Indemnification of Directors and Officers
  - -------------------------------------------------
  
       Section 145 of the Delaware General Corporation Law permits the Registrant
  to indemnify directors, officers, employees and agents of the Registrant against
  actual and reasonable expenses (including attorneys' fees) incurred by them in
  connection with any action, suit or proceeding brought against them by reason of
  their status or service as a director, officer, employee or agent by or on
  behalf of the Registrant, and against expenses (including attorneys' fees),
  judgments, fines and settlements actually and reasonably incurred by him in
  connection with any such action, suit or proceeding, if (i) he acted in good
  faith and in a manner he reasonably believed to be in or not opposed to the best
  interests of the Registrant, and (ii) in the case of a criminal proceeding, he
  had no reasonable cause to believe his conduct was unlawful. Except as ordered
  by a court, no indemnification shall be made in connection with any proceeding
  brought by or in the right of the corporation where the person involved is
  adjudged to be liable to the Registrant.
  
       Article EIGHTH of the Registrant's Restated Certificate of Incorporation
  provides that a director shall not be personally liable to the Registrant or its
  stockholders for monetary damages for breach of fiduciary duty as a director,
  except to the extent that elimination or limitation of liability is not
  permitted under the Delaware General Corporation Law as in effect when such
  liability is determined.
  
       Article NINTH of the Registrant's Restated Certificate of Incorporation
  provides that the Registrant shall, to the fullest extent permitted by the
  General Corporation Law of the State of Delaware, as amended from time to time,
  indemnify each person who was or is a party or is threatened to be made a party
  to any threatened, pending or completed action, suit or proceeding whether
  civil, criminal, administrative or investigative, by reason of the fact that he
  is or was, or has agreed to become a director or officer of the Registrant, or
  is or was serving, or has agreed to serve at the request of the Registrant as a
  director, officer or trustee of, or in a similar capacity with, another
  corporation, partnership, joint venture, trust or other enterprise. The
  indemnification provided for in Article NINTH is expressly not exclusive of any
  other rights to which those seeking indemnification may be entitled under any
  law, agreement or vote of stockholders or disinterested directors or otherwise,
  and shall inure to the benefit of the heirs, executors and administrators of
  such persons. Article NINTH further permits the Board of Directors to authorize
  the grant of indemnification rights to other employees and agents of the
  Registrant and such rights may be equivalent to, or greater or less than, those
  set forth in Article NINTH.
  
       Article V, Section 1 of the Registrant's By-Laws provides that the
  Registrant shall have the power to purchase and maintain insurance on behalf of
  any person who is or was a director, officer, employee or agent of the
  Registrant, or is or was serving at the request of the Registrant as a director,
  officer, employee or agent of another corporation, partnership, joint venture,
  trust or other enterprise against any liability asserted against such person and
  incurred by such person in any such capacity or arising out of such person's
  status as such.
  
       The Registrant maintains insurance for directors and officers and expects
  to enter into agreements with certain officers and directors affirming the
  Registrant's obligation to indemnify them to the fullest extent permitted by law
  and providing various other protections.
  
  Item 7. Exemption from Registration Claimed.
  - -------------------------------------------
  
           Not applicable.
  
                                       - 17 -
  18
  
  Item 8. Exhibits.
  - ----------------
  
       Exhibit Number                         Description
       --------------                         -----------
  
            4.1       Restated Certificate of Incorporation of the Registrant.
                      Filed as Exhibit 4.1 to the Company's Registration Statement
                      on Form S-8 (File No. 333-6779) and incorporated herein by
                      reference.
  
            4.2       Amended and Restated By-laws of the Registrant. Filed as
                      Exhibit 3.3 to the Company's Annual Report on Form 10-K for
                      the fiscal year ended December 31, 1995 and incorporated
                      herein by reference.
  
            4.3       Rights Agreement dated as of March 1, 1996 between the
                      Company and American Stock Transfer & Trust Company. Filed
                      as Exhibit 1 to the Company's Registration Statement on Form
                      8-A dated March 1, 1996 and incorporated herein by
                      reference.
  
            5.1       Opinion of Palmer & Dodge LLP as to the legality of the
                      securities registered hereunder.
  
           23.1       Consent of Ernst & Young LLP, independent auditors.
  
           23.2       Consent of Palmer & Dodge LLP (contained in Opinion of
                      Palmer & Dodge LLP, filed as Exhibit 5.1 hereto).
  
           24.1       Power of Attorney (set forth on the signature page to this
                      Registration Statement).
  
           24.2       Certified resolution of the Board of Directors authorizing
                      Power of Attorney.
  
           99.1       1992 Equity Incentive Plan, as amended through May 20, 1996.
  
  Item 9.  Undertakings.
  - ---------------------
  
       (a) The undersigned Registrant hereby undertakes:
  
           (1) To file, during any period in which offers or sales are being 
  made, a post-effective amendment to this registration statement:
  
               (i) To include any prospectus required by Section 10(a)(3) of the
  Securities Act of 1933;
  
               (ii) To reflect in the prospectus any facts or events arising 
  after the effective date of this Registration Statement (or the most recent
  post-effective amendment thereof) which, individually or in the aggregate,
  represents a fundamental change in the information set forth in this
  Registration Statement;
  
               (iii) To include any material information with respect to the 
  plan of distribution not previously disclosed in this Registration Statement or
  any material change to such information in this Registration Statement;
  
                                       - 18 -
  19
  
  PROVIDED, HOWEVER, that paragraphs (a)(1)(i) and (a)(1)(ii) do not apply if the
  information required to be included in a post-effective amendment by those
  paragraphs is contained in periodic reports filed by the Registrant pursuant to
  Section 13 or Section 15(d) of the Securities Exchange Act of 1934 that are
  incorporated by reference in this Registration Statement.
  
           (2) That, for the purpose of determining any liability under the 
  Securities Act of 1933, each such post-effective amendment shall be deemed to be
  a new registration statement relating to the securities offered therein, and the
  offering of such securities at that time shall be deemed to be the initial bona
  fide offering thereof.
  
           (3) To remove from registration by means of a post-effective amendment
  any of the securities being registered which remain unsold at the termination of
  the offering.
  
       (b) The undersigned Registrant hereby undertakes that, for purposes of
  determining any liability under the Securities Act of 1933, each filing of the
  Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
  Securities Exchange Act of 1934 that is incorporated by reference in this
  Registration Statement shall be deemed to be a new registration statement
  relating to the securities offered therein, and the offering of such securities
  at that time shall be deemed to be the initial bona fide offering thereof.
  
       (c) Insofar as indemnification for liabilities arising under the Securities
  Act of 1933 may be permitted to directors, officers and controlling persons of
  the Registrant pursuant to the provisions referred to in Item 6 hereof, or
  otherwise, the Registrant has been advised that in the opinion of the Securities
  and Exchange Commission such indemnification is against public policy as
  expressed in the Act and is, therefore, unenforceable. In the event that a claim
  for indemnification against such liabilities (other than the payment by the
  Registrant of expenses incurred or paid by a director, officer or controlling
  person of the registrant in the successful defense of any action, suit or
  proceeding) is asserted by such director, officer or controlling person in
  connection with the securities being registered, the Registrant will, unless in
  the opinion of its counsel the matter has been settled by controlling precedent,
  submit to a court of appropriate jurisdiction the question whether such
  indemnification by it is against public policy as expressed in the Act and will
  be governed by the final adjudication of such issue.
  
                                       - 19 -
  20
  
                                     SIGNATURES
  
       Pursuant to the requirements of the Securities Act of 1933, the Registrant
  certifies that it has reasonable grounds to believe that it meets all of the
  requirements for filing on Form S-8 and has duly caused this Registration
  Statement to be signed on its behalf by the undersigned, thereunto duly
  authorized, in the City of Waltham, State of Massachusetts, on this 19th day of
  July, 1996.
  
                                        GELTEX PHARMACEUTICALS, INC.
  
                                        By: /s/ Mark Skaletsky
                                            -------------------------------------
                                            Mark Skaletsky
                                            President and Chief Executive Officer
  
                                  POWER OF ATTORNEY
  
       We, the undersigned officers and directors of GelTex Pharmaceuticals, Inc.
  hereby severally constitute and appoint Mark Skaletsky and Peter Wirth, and each
  of them singly, our true and lawful attorneys-in-fact, with full power to them
  in any and all capacities, to sign any and all amendments to this Registration
  Statement on Form S-8 including any post-effective amendments thereto, and to
  file the same, with exhibits thereto and other documents in connection
  therewith, with the Securities and Exchange Commission, hereby ratifying and
  confirming all that each of said attorneys-in-fact may do or cause to be done by
  virtue hereof.
  
       Pursuant to the requirements of the Securities Act of 1933, this
  Registration Statement has been signed below by the following persons in the
  capacities and on the dates indicated:
  
           SIGNATURE            TITLE                               DATE
           ---------            -----                               ----
  
  /s/ Mark Skaletsky            President, Chief Executive          July 19, 1996
  - --------------------------    Officer and Treasurer               
  Mark Skaletsky                (Principal Executive                
                                Officer, Principal Financial Officer
                                and Principal Accounting Officer)   
                                                                    
  
  /s/ Robert J. Carpenter       Chairman of the Board               July 19, 1996
  - --------------------------    and Director
  Robert J. Carpenter           
  
  /s/ Ernest Parizeau           Director                            July 19, 1996
  - --------------------------
  Ernest Parizeau
  
                                       - 20 -
  21
  
           SIGNATURE             TITLE                     DATE
           ---------             -----                     ----
  
  /s/ Barbara A. Piette          Director                   July 19, 1996
  - --------------------------
  Barbara A. Piette
  
  /s/ James Tananbaum            Director                   July 19, 1996
  - --------------------------
  James Tananbaum
  
  /s/ Henri A. Termeer           Director                   July 19, 1996
  - --------------------------
  Henri A. Termeer
  
  /s/ Jesse Treu                 Director                   July 19, 1996
  - --------------------------
  Jesse Treu
  
  /s/ George Whitesides          Director                   July 19, 1996
  - --------------------------
  George Whitesides
  
                                       - 21 -
  22
  
                                            EXHIBIT INDEX
                                            -------------
  Exhibit Number                             Description                            Page Number
  - --------------                             -----------                            -----------
  4.1              Restated Certificate of Incorporation of the Registrant.         *
                        Filed as Exhibit 4.1 to the Company's Registration             
                        Statement on Form S-8 (File No. 333-6779).                     
                                                                                       
       4.2              Amended and Restated By-laws of the Registrant.                  *
                        Filed as Exhibit 3.3 to the Company's Annual Report            
                        on Form 10-K for the fiscal year ended December 31,            
                        1995.                                                          
                                                                                       
       4.3              Rights Agreement dated as of March 1, 1996 between               *
                        the Company and American Stock Transfer & Trust                
                        Company.  Filed as Exhibit 1 to the Company's                  
                        Registration Statement on Form 8-A dated March 1,              
                        1996.                                                          
                                                                                       
       5.1              Opinion of Palmer & Dodge LLP as to the legality of             23
                        the securities registered hereunder.                           
                                                                                       
      23.1              Consent of Ernst & Young LLP, independent auditors.             24
                                                                                       
      23.2              Consent of Palmer & Dodge LLP (contained in                     --
                        Opinion of Palmer & Dodge LLP, filed as Exhibit 5.1            
                        hereto).                                                       
                                                                                       
      24.1              Power of Attorney (set forth on the signature page to           --
                        this Registration Statement).                                  
                                                                                       
      24.2              Certified resolution of the Board of Directors                  25
                        authorizing Power of Attorney.                                 
                                                                                       
      99.1              1992 Equity Incentive Plan, as amended through                  26
                        May 20, 1996.
  - ----------------------------
  
  *  Incorporated herein by reference.
  - 22 -