content: <PAGE>   1
        As filed with the Securities and Exchange Commission on June 30, 2000
  
                                                         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>
  <CAPTION>
  <S>                                                            <C>
                   DELAWARE                                                   04-3136767
  (State or other jurisdiction of incorporation)                 (I.R.S. Employer Identification No.)
  </TABLE>
  
           153 SECOND AVENUE, WALTHAM, MASSACHUSETTS 02451 (781) 290-5888
     (Address and telephone number of registrant's principal executive offices)
  
  
  
                           1995 DIRECTOR STOCK OPTION PLAN
                              (Full Title of the Plan)
  
                MARK SKALETSKY, PRESIDENT AND CHIEF EXECUTIVE OFFICER
                            GelTex Pharmaceuticals, Inc.
                                  153 Second Avenue
                            Waltham, Massachusetts 02451
                                   (781) 290-5888
              (Name, address and telephone number of agent for service)
  
                                   with copies to:
  
                             LYNNETTE C. FALLON, ESQUIRE
                                 Palmer & Dodge LLP
                                  One Beacon Street
                             Boston, Massachusetts 02108
                                   (617) 573-0100
  
  
  
                           CALCULATION OF REGISTRATION FEE
  
  <TABLE>
  <CAPTION>
  Title of each class of securities      Amount to be       Proposed maximum     Proposed maximum        Amount of
           to be registered               registered       offering price per   aggregate offering    registration fee
                                                               share (1)             price (1)
  ----------------------------------------------------------------------------------------------------------------------
  <S>                                <C>                   <C>                  <C>                    <C>
  Common Stock, $0.01 par value      40,000 shares (2)         $19.53125             $781,250             $206.25
  
  ----------------------------------------------------------------------------------------------------------------------
  
  ======================================================================================================================
  </TABLE>
  (1)  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 June 26, 2000 as reported by the Nasdaq National Market.
  (2)  This Registration Statement registers an additional 40,000 shares under the
       1995 Director Stock Option Plan, under which 110,000 shares have been
       previously registered (SEC File Nos. 333-06779 and 333-60699).
  
  
  <PAGE>   2
  
  
     STATEMENT REGARDING INCORPORATION BY REFERENCE FROM EFFECTIVE REGISTRATION
                                     STATEMENT.
  
       Pursuant to Instruction E to Form S-8, the contents of the Registrant's
  Registration Statement on Form S-8 filed with the Securities and Exchange
  Commission on August 5, 1998 (File No. 333-60699) relating to the registration
  of 35,000 additional shares of the Registrant's Common Stock, $0.01 par value
  per share (the "Common Stock"), authorized for issuance under the Registrant's
  1995 Director Stock Option Plan (the "Plan"), are incorporated by reference in
  their entirety in this Registration Statement, except as to the items set forth
  below. This Registration Statement provides for the registration of an
  additional 40,000 shares of the Registrant's Common Stock to be issued under the
  Plan.
  
  
                                         1
  <PAGE>   3
  
  
                                       PART II
                 INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
  
  
  ITEM 8.  EXHIBITS.
  
           See Exhibit Index on page 4.
  
  
                                         2
  <PAGE>   4
  
  
                                     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 29th day of
  June 2000.
  
                                              GELTEX PHARMACEUTICALS, INC.
  
  
                                              By: /s/ Mark Skaletsky
                                                  ------------------
                                                  Mark Skaletsky
                                                  President
  
                                  POWER OF ATTORNEY
  
       We, the undersigned officers and directors of GelTex Pharmaceuticals, Inc.
  hereby severally constitute and appoint Mark Skaletsky and Joann Nestor, 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:
  
  <TABLE>
  <CAPTION>
           SIGNATURE                          TITLE                                                DATE
  
  
  <S>                                         <C>                                                  <C>
  /s/ Mark Skaletsky                          President (Principal Executive Officer)              June 29, 2000
  ------------------------------------        and Director
  Mark Skaletsky
  
  
  /s/ Paul J. Mellett, Jr.                    Vice President Administration and Finance            June 29, 2000
  ------------------------------------        (Principal Financial and Accounting Officer)
  Paul J. Mellett, Jr.
  
  
  /s/ Robert J. Carpenter                     Director                                             June 29, 2000
  ------------------------------------
  Robert J. Carpenter
  
  
                                              Director                                             June __, 2000
  ------------------------------------
  J. Richard Crout
  
  
  /s/ Henri A. Termeer                        Director                                             June 29, 2000
  ------------------------------------
  Henri A. Termeer
  
  
  /s/ Jesse Treu                              Director                                             June 29, 2000
  ------------------------------------
  Jesse Treu
  </TABLE>
  
  
                                         3
  <PAGE>   5
  
  
                                    EXHIBIT INDEX
  
  <TABLE>
  <CAPTION>
  Exhibit No.                                     Description
  -----------                                     -----------
  
  <S>            <C>
  4.1            Amended and Restated By-Laws of Registrant Filed as Exhibit 3.3 to Registrant's
                 Annual Report on Form 10-K for the fiscal year ended December 31, 1995 and
                 incorporated herein by reference.
  
  4.2            Specimen certificate for shares of common stock of Registrant  Filed as Exhibit 4.1 to
                 Registrant's Registration Statement on Form S-1 (File No. 33-97322) and incorporated herein by
                 reference.
  
  4.3            Amended and Restated Facility One Term Note issued by Registrant to Fleet National Bank, dated
                 as of May 21, 1997.  Filed as Exhibit 4.1 to Registrant's Quarterly Report on Form 10-Q for the
                 quarter ended June 30, 1998 and incorporated herein by reference.
  
  4.4            Second Loan Modification Agreement between Registrant and Fleet National Bank, dated as of June
                 30, 1998.  Filed as Exhibit 4.2 to Registrant's Quarterly Report on Form 10-Q for the quarter
                 ended June 30, 1998 and incorporated herein by reference.
  
  4.5            Letter Agreement between Registrant and Fleet National Bank dated October 4, 1999.  Filed as
                 Exhibit 4.1 to Registrant's Quarterly Report on Form 10-Q for the quarter ended September 30,
                 1999 and incorporated herein by reference.
  
  4.6            Promissory Note, dated October 4, 1999 issued by Registrant to Fleet National Bank.
                 Filed as Exhibit 4.2 to Registrant's Quarterly Report on Form 10-Q for the quarter ended
                 September 30, 1999 and incorporated herein by reference.
  
  5              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 PricewaterhouseCoopers LLP, independent accountants.
  
  23.3           Consent of Palmer & Dodge LLP (contained in opinion filed as Exhibit 5 hereto).
  
  24             Power of Attorney (set forth on the signature page of this Registration Statement).
  
  </TABLE>
  
  
                                         4
metadata_documents: [{"type": "S-8", "sequence": "1", "filename": "s-8.txt", "description": "GELTEX PHARMACEUTICALS", "secsgml_size_bytes": 9685}]
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": "333-40510", "film-number": "665757"}, "business-address": {"street1": "153 SECOND AVE", "city": "WALTHAM", "state": "MA", "zip": "02451", "phone": "781-290-58"}, "mail-address": {"street1": "152 SECOND AVE", "city": "WALTHAM", "state": "MA", "zip": "02451"}}
text: 1
        As filed with the Securities and Exchange Commission on June 30, 2000
  
                                                         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.)
  153 SECOND AVENUE, WALTHAM, MASSACHUSETTS 02451 (781) 290-5888
     (Address and telephone number of registrant's principal executive offices)
  
                           1995 DIRECTOR STOCK OPTION PLAN
                              (Full Title of the Plan)
  
                MARK SKALETSKY, PRESIDENT AND CHIEF EXECUTIVE OFFICER
                            GelTex Pharmaceuticals, Inc.
                                  153 Second Avenue
                            Waltham, Massachusetts 02451
                                   (781) 290-5888
              (Name, address and telephone number of agent for service)
  
                                   with copies to:
  
                             LYNNETTE C. FALLON, ESQUIRE
                                 Palmer & Dodge LLP
                                  One Beacon Street
                             Boston, Massachusetts 02108
                                   (617) 573-0100
  
                           CALCULATION OF REGISTRATION FEE
  Title of each class of securities      Amount to be       Proposed maximum     Proposed maximum        Amount of
           to be registered               registered       offering price per   aggregate offering    registration fee
                                                               share (1)             price (1)
  ----------------------------------------------------------------------------------------------------------------------
  Common Stock, $0.01 par value      40,000 shares (2)         $19.53125             $781,250             $206.25
  
  ----------------------------------------------------------------------------------------------------------------------
  
  ======================================================================================================================
  (1)  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 June 26, 2000 as reported by the Nasdaq National Market.
  (2)  This Registration Statement registers an additional 40,000 shares under the
       1995 Director Stock Option Plan, under which 110,000 shares have been
       previously registered (SEC File Nos. 333-06779 and 333-60699).
  2
  
     STATEMENT REGARDING INCORPORATION BY REFERENCE FROM EFFECTIVE REGISTRATION
                                     STATEMENT.
  
       Pursuant to Instruction E to Form S-8, the contents of the Registrant's
  Registration Statement on Form S-8 filed with the Securities and Exchange
  Commission on August 5, 1998 (File No. 333-60699) relating to the registration
  of 35,000 additional shares of the Registrant's Common Stock, $0.01 par value
  per share (the "Common Stock"), authorized for issuance under the Registrant's
  1995 Director Stock Option Plan (the "Plan"), are incorporated by reference in
  their entirety in this Registration Statement, except as to the items set forth
  below. This Registration Statement provides for the registration of an
  additional 40,000 shares of the Registrant's Common Stock to be issued under the
  Plan.
  
                                         1
  3
  
                                       PART II
                 INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
  
  ITEM 8.  EXHIBITS.
  
           See Exhibit Index on page 4.
  
                                         2
  4
  
                                     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 29th day of
  June 2000.
  
                                              GELTEX PHARMACEUTICALS, INC.
  
                                              By: /s/ Mark Skaletsky
                                                  ------------------
                                                  Mark Skaletsky
                                                  President
  
                                  POWER OF ATTORNEY
  
       We, the undersigned officers and directors of GelTex Pharmaceuticals, Inc.
  hereby severally constitute and appoint Mark Skaletsky and Joann Nestor, 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 (Principal Executive Officer)              June 29, 2000
  ------------------------------------        and Director
  Mark Skaletsky
  
  /s/ Paul J. Mellett, Jr.                    Vice President Administration and Finance            June 29, 2000
  ------------------------------------        (Principal Financial and Accounting Officer)
  Paul J. Mellett, Jr.
  
  /s/ Robert J. Carpenter                     Director                                             June 29, 2000
  ------------------------------------
  Robert J. Carpenter
  
                                              Director                                             June __, 2000
  ------------------------------------
  J. Richard Crout
  
  /s/ Henri A. Termeer                        Director                                             June 29, 2000
  ------------------------------------
  Henri A. Termeer
  
  /s/ Jesse Treu                              Director                                             June 29, 2000
  ------------------------------------
  Jesse Treu
  3
  5
  
                                    EXHIBIT INDEX
  Exhibit No.                                     Description
  -----------                                     -----------
  4.1            Amended and Restated By-Laws of Registrant Filed as Exhibit 3.3 to Registrant's
                 Annual Report on Form 10-K for the fiscal year ended December 31, 1995 and
                 incorporated herein by reference.
  
  4.2            Specimen certificate for shares of common stock of Registrant  Filed as Exhibit 4.1 to
                 Registrant's Registration Statement on Form S-1 (File No. 33-97322) and incorporated herein by
                 reference.
  
  4.3            Amended and Restated Facility One Term Note issued by Registrant to Fleet National Bank, dated
                 as of May 21, 1997.  Filed as Exhibit 4.1 to Registrant's Quarterly Report on Form 10-Q for the
                 quarter ended June 30, 1998 and incorporated herein by reference.
  
  4.4            Second Loan Modification Agreement between Registrant and Fleet National Bank, dated as of June
                 30, 1998.  Filed as Exhibit 4.2 to Registrant's Quarterly Report on Form 10-Q for the quarter
                 ended June 30, 1998 and incorporated herein by reference.
  
  4.5            Letter Agreement between Registrant and Fleet National Bank dated October 4, 1999.  Filed as
                 Exhibit 4.1 to Registrant's Quarterly Report on Form 10-Q for the quarter ended September 30,
                 1999 and incorporated herein by reference.
  
  4.6            Promissory Note, dated October 4, 1999 issued by Registrant to Fleet National Bank.
                 Filed as Exhibit 4.2 to Registrant's Quarterly Report on Form 10-Q for the quarter ended
                 September 30, 1999 and incorporated herein by reference.
  
  5              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 PricewaterhouseCoopers LLP, independent accountants.
  
  23.3           Consent of Palmer & Dodge LLP (contained in opinion filed as Exhibit 5 hereto).
  
  24             Power of Attorney (set forth on the signature page of this Registration Statement).
  4