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  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>As
  filed with the United States Securities and Exchange Commission on
  September 15, 2005</B>
  </DIV>
  
  
  <DIV align="right" style="font-size: 10pt; margin-top: 12pt"><B>Registration No.&nbsp;333-________</B>
  </DIV>
  
  
  <DIV style="width: 100%; border-bottom: 2pt solid black; font-size: 1pt">&nbsp;</DIV>
  <DIV style="width: 100%; border-bottom: 1pt solid black; font-size: 1pt">&nbsp;</DIV>
  
  
  
  
  <DIV align="center" style="font-size: 14pt; margin-top: 12pt"><B>UNITED STATES SECURITIES AND EXCHANGE COMMISSION</B>
  </DIV>
  
  <DIV align="center" style="font-size: 12pt"><B>Washington, D.C. 20549</B>
  </DIV>
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><DIV align="center"><DIV style="font-size: 3pt; margin-top: 16pt; width: 26%; border-top: 1px solid #000000">&nbsp;</DIV></DIV>
  </DIV>
  
  <DIV align="center" style="font-size: 18pt; margin-top: 12pt"><B>FORM S-8</B>
  </DIV>
  
  
  <DIV align="center" style="font-size: 12pt; margin-top: 12pt"><B>REGISTRATION STATEMENT<BR>
  UNDER THE SECURITIES ACT OF 1933</B>
  </DIV>
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><DIV align="center"><DIV style="font-size: 3pt; margin-top: 16pt; width: 26%; border-top: 1px solid #000000">&nbsp;</DIV></DIV>
  </DIV>
  
  <DIV align="center" style="font-size: 24pt; margin-top: 12pt"><B>BIOGEN IDEC INC.</B>
  </DIV>
  
  <DIV align="center" style="font-size: 10pt">(Exact name of registrant as specified in its charter)</DIV>
  
  
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="47%">&nbsp;</TD>
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  </TR>
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  <TR valign="bottom">
      <TD align="center" valign="top"><B>Delaware</B>
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="top"><B>33-0112644</B></TD>
  </TR>
  <TR valign="bottom">
      <TD align="center" valign="top">(State or other jurisdiction of<BR>
  incorporation or organization)
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="top">(I.R.S. Employer Identification No.)</TD>
  </TR>
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>14 Cambridge Center<BR>
  Cambridge, Massachusetts 02142</B><BR>
  (Address of Principal Executive Offices) (Zip Code)
  </DIV>
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><DIV align="center"><DIV style="font-size: 3pt; margin-top: 16pt; width: 26%; border-top: 1px solid #000000">&nbsp;</DIV></DIV>
  </DIV>
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>Biogen Idec Inc. 2005 Omnibus Equity Plan<BR>
  Biogen Idec Inc. 1995 Employee Stock Purchase Plan</B><BR>
  (Full title of the plan)<BR>
  <DIV align="center"><DIV style="font-size: 3pt; margin-top: 16pt; width: 26%; border-top: 1px solid #000000">&nbsp;</DIV></DIV>
  </DIV>
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>Peter N. Kellogg<BR>
  Executive Vice President, Finance and Chief Financial Officer<BR>
  Biogen Idec Inc.<BR>
  14 Cambridge Center<BR>
  Cambridge, Massachusetts 02142<BR>
  (617)&nbsp;679-2000</B><BR>
  (Name, address and telephone number, including area code, of agent for service)
  </DIV>
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><DIV align="center"><DIV style="font-size: 3pt; margin-top: 16pt; width: 26%; border-top: 1px solid #000000">&nbsp;</DIV></DIV>
  </DIV>
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>CALCULATION OF REGISTRATION FEE</B>
  </DIV>
  
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="1%">&nbsp;</TD>
      <TD width="54%">&nbsp;</TD>
      <TD width="2%">&nbsp;</TD><!-- VRule -->
      <TD width="2%">&nbsp;</TD>
      <TD width="7%">&nbsp;</TD>
      <TD width="2%">&nbsp;</TD><!-- VRule -->
      <TD width="2%">&nbsp;</TD>
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      <TD width="7%">&nbsp;</TD>
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      <TD width="2%">&nbsp;</TD>
      <TD width="7%">&nbsp;</TD>
  
      <TD width="1%">&nbsp;</TD>
  </TR><TR style="font-size: 1px" valign="bottom">
      <TD nowrap align="left" colspan="15" style="border-bottom: 3px solid #000000">&nbsp;</TD>
  </TR>
  <TR style="font-size: 8pt" valign="bottom">    <TD width="1%">&nbsp;</TD>
  
      <TD>&nbsp;</TD>
      <TD style="border-right: 2px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>Amount to Be</B></TD>
      <TD style="border-right: 2px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>Proposed Maximum</B></TD>
      <TD style="border-right: 2px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>Proposed Maximum</B></TD>
      <TD style="border-right: 2px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>Amount of</B></TD>
      <TD width="1%">&nbsp;</TD>
  </TR>
  <TR style="font-size: 8pt" valign="bottom">    <TD width="1%">&nbsp;</TD>
  
      <TD>&nbsp;</TD>
      <TD style="border-right: 2px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>Registered</B></TD>
      <TD style="border-right: 2px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>Offering Price per</B></TD>
      <TD style="border-right: 2px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>Aggregate Offering</B></TD>
      <TD style="border-right: 2px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>Registration Fee</B></TD>
      <TD width="1%">&nbsp;</TD>
  </TR>
  <TR style="font-size: 8pt" valign="bottom">    <TD width="1%">&nbsp;</TD>
  
      <TD nowrap align="left"><B>Title of Securities To Be Registered</B></TD>
      <TD style="border-right: 2px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>(1)(2)(3)</B></TD>
      <TD style="border-right: 2px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>Share (4)</B></TD>
      <TD style="border-right: 2px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>Price (4)</B></TD>
      <TD style="border-right: 2px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>(5)</B></TD>
      <TD width="1%">&nbsp;</TD>
  </TR>
  
  <!-- End Table Head -->
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      <TD width="1%" style="border-top: 2px solid #000000">&nbsp;</TD>
                      <TD valign="top" style="border-top: 2px solid #000000"><DIV style="margin-left:0px; text-indent:-0px">Common stock, $0.0005 par value per
  share (including the associated rights
  to purchase Series&nbsp;X junior
  participating preferred stock)(2)
  </DIV></TD>
      <TD style="border-right: 2px solid #000000; border-top: 2px solid #000000">&nbsp;</TD>
      <TD style="border-top: 2px solid #000000">&nbsp;</TD>
      <TD align="left" valign="top" style="border-top: 2px solid #000000">20,857,448 shares
  </TD>
      <TD style="border-right: 2px solid #000000; border-top: 2px solid #000000">&nbsp;</TD>
      <TD style="border-top: 2px solid #000000">&nbsp;</TD>
  
  <TD align="left" valign="top" style="border-top: 2px solid #000000">$41.04
  </TD>
      <TD style="border-right: 2px solid #000000; border-top: 2px solid #000000">&nbsp;</TD>
      <TD style="border-top: 2px solid #000000">&nbsp;</TD>
  
  <TD align="left" valign="top" style="border-top: 2px solid #000000">$855,989,666
  </TD>
      <TD style="border-right: 2px solid #000000; border-top: 2px solid #000000">&nbsp;</TD>
      <TD style="border-top: 2px solid #000000">&nbsp;</TD>
  
  <TD align="left" valign="top" style="border-top: 2px solid #000000">$93,915</TD>
      <TD width="1%" style="border-top: 2px solid #000000">&nbsp;</TD>
  </TR>
  <TR style="font-size: 1px" valign="bottom">
      <TD nowrap align="left" colspan="15" style="border-top: 3px solid #000000">&nbsp;</TD>
  </TR>
  
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  <DIV style="margin-top: 6pt">
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="1%" nowrap align="left">(1)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>Includes 18,857,448 shares issuable under the Biogen Idec Inc. 2005 Omnibus Equity Plan (the
  &#147;2005 Plan&#148;) and 2,000,000 shares issuable under the Biogen Idec Inc. 1995 Employee Stock
  Purchase Plan, as amended and restated (the &#147;ESPP&#148;). The aggregate number of shares to be
  registered is subject to adjustment by reason of stock splits, stock dividends and other
  events pursuant to the terms of the 2005 Plan or the ESPP, as applicable. Accordingly,
  pursuant to Rule&nbsp;416 under the Securities Act of 1933, as amended (the &#147;Securities Act&#148;), this
  Registration Statement covers, in addition to the number of shares of common stock shown in
  the table above, an indeterminate number of shares of the Registrant&#146;s common stock which may
  be subject to grant or otherwise issuable by operation of the provisions of the 2005 Plan or
  the ESPP governing such adjustments.</TD>
  </TR>
  
  </TABLE>
  </DIV>
  
  <DIV style="margin-top: 6pt">
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="1%" nowrap align="left">(2)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>This Registration Statement also covers the rights to purchase shares of the Registrant&#146;s
  Series&nbsp;X junior participating preferred stock issuable in accordance with the Amended and
  Restated Rights Agreement, dated as of July&nbsp;26, 2001, between the Registrant and Mellon
  Investor Services LLC, as amended. These rights initially are attached to and trade
  with the Registrant&#146;s common stock. The value attributed to such rights, if any, is
  reflected in the market price of the Registrant&#146;s common stock.</TD>
  </TR>
  
  </TABLE>
  </DIV>
  
  <DIV style="margin-top: 6pt">
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="1%" nowrap align="left">(3)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>The Registrant is carrying forward to this Registration Statement 3,857,448 shares of the
  Registrant&#146;s common stock (including the associated rights to purchase Series&nbsp;X junior
  participating preferred stock) previously registered under its Registration Statement on Form
  S-8 (SEC File No.&nbsp;333-110432).</TD>
  </TR>
  
  </TABLE>
  </DIV>
  
  <DIV style="margin-top: 6pt">
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="1%" nowrap align="left">(4)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>Estimated pursuant to Rule 457(h) of the Securities Act, solely for the purpose of
  calculating the registration fee, on the basis of the average of the high and low selling
  prices of the Registrant&#146;s common stock as reported on the
  Nasdaq National Market on September&nbsp;14, 2005. The filing fee
  payable is $100,750. Of this amount, the Registrant offsets
  $6,836 in fees previously paid with respect to the shares of common stock carried forward to
  this Registration Statement from Registration Statement on Form S-8 (SEC File No.&nbsp;333-110432).
  The remaining amount of fees payable of $93,915 has been transmitted as of the date hereof.</TD>
  </TR>
  
  </TABLE>
  </DIV>
  
  <DIV style="margin-top: 6pt">
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="1%" nowrap align="left">(5)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>The registration fee has been calculated pursuant to Section 6(b) of the Securities Act by
  multiplying .0001177 by the proposed maximum aggregate offering price (as computed in
  accordance with Rule&nbsp;457 under the Securities Act solely for the purpose of determining the
  registration fee of the securities registered hereby).</TD>
  </TR>
  
  </TABLE>
  </DIV>
  
  <DIV style="width: 100%; border-bottom: 1pt solid black; margin-top: 10pt; font-size: 1pt">&nbsp;</DIV>
  <DIV style="width: 100%; border-bottom: 2pt solid black; font-size: 1pt">&nbsp;</DIV>
  
  
  
  
  
  <P align="center" style="font-size: 10pt">
  </DIV>
  
  <!-- PAGEBREAK -->
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  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  
  
  
  <!-- TOC -->
  <A name="toc"><DIV align="CENTER" style="page-break-before:always"><U><B>TABLE OF CONTENTS</B></U></DIV></A>
  
  <P><CENTER>
  <TABLE border="0" width="90%" cellpadding="0" cellspacing="0">
  <TR>
  	<TD width="3%"></TD>
  	<TD width="3%"></TD>
  	<TD width="3%"></TD>
  	<TD width="3%"></TD>
  	<TD width="3%"></TD>
  	<TD width="3%"></TD>
  	<TD width="3%"></TD>
  	<TD width="3%"></TD>
  	<TD width="76%"></TD>
  </TR>
  <TR><TD></TD><TD colspan="8"><A HREF="#000">PART I</A></TD></TR>
  <TR><TD></TD><TD colspan="8"><A HREF="#001">PART II</A></TD></TR>
  <TR><TD></TD><TD colspan="8"><A HREF="#002">Item&nbsp;3: Incorporation of Documents by Reference</A></TD></TR>
  <TR><TD></TD><TD colspan="8"><A HREF="#003">Item&nbsp;4: Description of Securities</A></TD></TR>
  <TR><TD></TD><TD colspan="8"><A HREF="#004">Item&nbsp;5: Interests of Named Experts and Counsel</A></TD></TR>
  <TR><TD></TD><TD colspan="8"><A HREF="#005">Item&nbsp;6: Indemnification of Directors and Officers</A></TD></TR>
  <TR><TD></TD><TD colspan="8"><A HREF="#006">Item&nbsp;7: Exemption from Registration Claimed</A></TD></TR>
  <TR><TD></TD><TD colspan="8"><A HREF="#007">Item&nbsp;8: Exhibits</A></TD></TR>
  <TR><TD></TD><TD colspan="8"><A HREF="#008">Item&nbsp;9: Undertakings</A></TD></TR>
  <TR><TD colspan="9"><A HREF="#009">SIGNATURES</A></TD></TR>
  <TR><TD colspan="9"><A HREF="#010">POWER OF ATTORNEY</A></TD></TR>
  <TR><TD colspan="9"><A HREF="b56683biexv5w1.htm">EX-5.1 OPINION OF SKADDEN, ARPS, SLATE, MEAGHER & FLOM LLP</A></TD></TR>
  <TR><TD colspan="9"><A HREF="b56683biexv23w1.htm">EX-23.1 CONSENT OF PRICEWATERHOUSECOOPERS LLP</A></TD></TR>
  <TR><TD colspan="9"><A HREF="b56683biexv23w2.htm">EX-23.2 CONSENT OF KPMG LLP</A></TD></TR>
  </TABLE>
  </CENTER>
  <!-- /TOC -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  
  
  
  
  <!-- link2 "PART I" -->
  <DIV align="left"><A NAME="000"></A></DIV>
  
  <DIV align="center" style="font-size: 10pt; margin-top: 12pt"><B>PART I</B>
  </DIV>
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 6pt"><B>INFORMATION REQUIRED IN THE SECTION 10(A) PROSPECTUS</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The documents containing the information specified in Part&nbsp;I have been sent or given to
  employees as specified by Rule&nbsp;428(b)(1). Such documents are not being filed with the Securities
  and Exchange Commission (the &#147;Commission&#148;) either as part of this Registration Statement or as
  prospectuses or prospectus supplements pursuant to Rule&nbsp;424. Such documents and the documents
  incorporated by reference in this Registration Statement pursuant to Item&nbsp;3 of Part&nbsp;II of this
  Form, taken together, constitute a prospectus that meets the requirements of Section 10(a) of the
  Securities Act.
  </DIV>
  <!-- link2 "PART II" -->
  <DIV align="left"><A NAME="001"></A></DIV>
  
  <DIV align="center" style="font-size: 10pt; margin-top: 12pt"><B>PART II</B>
  </DIV>
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 6pt"><B>INFORMATION REQUIRED IN THE REGISTRATION STATEMENT</B>
  </DIV>
  
  <!-- link2 "Item&nbsp;3: Incorporation of Documents by Reference" -->
  <DIV align="left"><A NAME="002"></A></DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 12pt"><B>Item&nbsp;3: Incorporation of Documents by Reference</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The Registrant hereby incorporates by reference into this Registration Statement the following
  documents, which have been previously filed by the Registrant with the Commission:
  </DIV>
  
  <DIV style="margin-top: 6pt">
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="2%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(1)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>Registrant&#146;s Annual Report on Form 10-K for the year ended December&nbsp;31, 2004
  filed with the Commission on March&nbsp;31, 2005;</TD>
  </TR>
  
  <TR>
      <TD style="font-size: 6pt">&nbsp;</TD>
  </TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="2%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(2)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>Registrant&#146;s Quarterly Report on Form 10-Q for the quarter ended March&nbsp;31, 2005
  filed with the Commission on April&nbsp;29, 2005;</TD>
  </TR>
  
  <TR>
      <TD style="font-size: 6pt">&nbsp;</TD>
  </TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="2%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(3)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>Registrant&#146;s Quarterly Report on Form 10-Q for the quarter ended June&nbsp;30, 2005
  filed with the Commission on July&nbsp;27, 2005;</TD>
  </TR>
  
  <TR>
      <TD style="font-size: 6pt">&nbsp;</TD>
  </TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="2%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(4)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>Registrant&#146;s Current Reports on Form 8-K filed with the Commission on January
  6, 2005, February&nbsp;22, 2005, February&nbsp;24, 2005, March&nbsp;3, 2005, March&nbsp;7, 2005, March&nbsp;23,
  2005, April&nbsp;1, 2005 (as to Items 8.01 and 9.01 only), May&nbsp;3, 2005, May&nbsp;11, 2005, June
  6, 2005, June&nbsp;16, 2005, August&nbsp;11, 2005 and
  September&nbsp;13, 2005;</TD>
  </TR>
  
  <TR>
      <TD style="font-size: 6pt">&nbsp;</TD>
  </TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="2%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(5)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>Registrant&#146;s Definitive Proxy Statement on Form&nbsp;DEF14A filed on April&nbsp;15, 2005;</TD>
  </TR>
  
  <TR>
      <TD style="font-size: 6pt">&nbsp;</TD>
  </TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="2%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(6)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>The description of the Registrant&#146;s common stock contained in the Registration
  Statement on Form 8-B filed with the Commission on June&nbsp;2, 1997, including any
  amendment or report updating such description of the common stock; and</TD>
  </TR>
  
  <TR>
      <TD style="font-size: 6pt">&nbsp;</TD>
  </TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="2%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(7)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>The description of the Registrant&#146;s preferred stock purchase rights contained
  in its Registration Statement on Form 8-A filed with the Commission on August&nbsp;1, 1997,
  as amended by Form 8-A/A filed with the Commission on July&nbsp;27, 2001 and Form&nbsp;8&#150;A/A
  filed with the Commission on June&nbsp;25, 2003, including any amendment or report updating
  such description of the such preferred stock purchase rights.</TD>
  </TR>
  
  </TABLE>
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Until such time that a post-effective amendment to this Registration Statement has been filed
  which indicates that all securities offered hereby have been sold or which deregisters all
  securities remaining unsold at the time of such amendment, all documents subsequently filed by the
  Registrant pursuant to Sections&nbsp;13(a), 13(c), 14 and 15(d) of the Securities Exchange Act of 1934,
  as amended (the
  </DIV>
  
  <P align="center" style="font-size: 10pt">2
  </DIV>
  
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  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&#147;Exchange Act&#148;), shall be deemed to be incorporated by reference in this Registration
  Statement and to be a part hereof from the date of filing of such documents.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Any statement contained herein or in a document incorporated or deemed to be incorporated by
  reference herein shall be deemed to be modified or superseded for purposes of this Registration
  Statement to the extent that a statement contained herein or in any subsequently filed document
  which is also deemed to be incorporated by reference herein modifies or supersedes such statement.
  Any such statement so modified or superseded shall not be deemed, except as so modified or
  superseded, to constitute a part of this Registration Statement.
  </DIV>
  <!-- link2 "Item&nbsp;4: Description of Securities" -->
  <DIV align="left"><A NAME="003"></A></DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 12pt"><B>Item&nbsp;4: Description of Securities</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The class of securities being offered by this Registration Statement is registered under
  Section&nbsp;12 of the Securities Exchange Act of 1934. The Registrant provides the below description
  to update the description of its common stock contained in its Registration Statement on Form 8-B
  filed with the Commission on June&nbsp;2, 1997.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Under
  the Registrant&#146;s Amended and Restated Certificate of
  Incorporation, as amended (the &#147;Certificate of
  Incorporation&#148;), the Registrant&#146;s
  authorized capital stock consists of 1,000,000,000 shares of common stock, $0.0005 par value per
  share, and 8,000,000 shares of preferred stock, $0.001 par value per share. As of June&nbsp;30, 2005,
  1,750,000 shares of preferred stock were designated as Series&nbsp;A preferred stock and 1,000,000
  shares of preferred stock were reserved for issuance as Series&nbsp;X junior participating preferred
  stock in connection with the Registrant&#146;s preferred stock purchase rights described in the
  Registrant&#146;s Registration Statement on Form 8-A filed with the Commission on August&nbsp;1, 1997, as
  amended by Form 8-A/A filed with the Commission on July&nbsp;27, 2001 and Form&nbsp;8&#150;A/A filed with the
  Commission on June&nbsp;25, 2003, including any amendment or report updating such description of the
  such preferred stock purchase rights. As of June&nbsp;30, 2005, there were outstanding 337,836,891
  shares of common stock and 8,221 shares of Series&nbsp;A-2 preferred stock.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B><I>Registrant Common Stock</I></B>
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<I>Voting Rights</I>. Each holder of common stock is entitled to one vote for each share of common
  stock held of record on the applicable record date on all matters submitted to a vote of
  stockholders.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<I>Dividend Rights; Rights Upon Liquidation</I>. The holders of common stock are entitled to
  receive, from funds legally available for the payment thereof, dividends when and as declared by
  resolution of the Registrant&#146;s board of directors, subject to any preferential dividend rights
  granted to the holders of any outstanding preferred stock. In the event of a liquidation,
  dissolution or winding up of the Registrant, each share of common stock is entitled to share pro
  rata in any distribution of the Registrant&#146;s assets after payment or providing for the payment of
  liabilities and the liquidation preference of any outstanding preferred stock.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<I>Preemptive Rights</I>. Holders of common stock have no preemptive rights to purchase, subscribe
  for or otherwise acquire any unissued or treasury shares or other securities.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<I>Transfer Agent and Registrar</I>. The transfer agent and registrar for common stock is Equiserve
  Trust Company, N.A.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B><I>Description of Preferred Stock</I></B>
  </DIV>
  
  <P align="center" style="font-size: 10pt">3
  </DIV>
  
  <!-- PAGEBREAK -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Pursuant
  to the Certificate of Incorporation, the
  Registrant&#146;s board of directors is authorized to issue up to an aggregate of 8,000,000 shares of
  preferred stock in one or more series and to fix the rights, preferences, privileges and
  restrictions, including the dividend rights, conversion rights, voting rights, rights and terms of
  redemption, redemption price or prices, liquidation preferences and the number of shares
  constituting any series or the designations of such series, without any further vote or action by
  the stockholders. The issuance of preferred stock in certain circumstances may have the effect of
  delaying, deferring or preventing a change of control of the Registrant without further actions of
  the stockholders. The issuance of preferred stock with voting and conversion rights may adversely
  affect the voting power of the holders of common stock, including the loss of voting control to
  others.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B><I>Preferred Stock Outstanding</I></B>. As of June&nbsp;30, 2005, there were 8,221 shares of Series&nbsp;A-2
  preferred stock outstanding, all of which are owned by Genentech, Inc., and no other shares of
  preferred stock outstanding. The outstanding shares of Series&nbsp;A-2 preferred stock are duly
  authorized, validly issued, fully paid and non-assessable.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<I>Voting Rights. </I>None of the Series&nbsp;A-2 preferred stock outstanding has voting rights, except
  as may be required by the Delaware General Corporation Law (the &#147;DGCL&#148;).
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<I>Conversion. </I>Each share of Series&nbsp;A-2 preferred stock is convertible at any time into 60
  shares of the Registrant&#146;s common stock. The outstanding shares of Series&nbsp;A-2 preferred stock
  automatically convert into common stock in the event that a person or entity other than Genentech
  or its affiliate acquires such shares. The conversion rate of the Series&nbsp;A-2 preferred stock is
  subject to adjustment for certain stock splits, stock dividends, combinations and other events.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<I>Dividend Rights; Rights Upon Liquidation. </I>
  Under the terms of the outstanding Series&nbsp;A-2
  preferred stock as set forth in the Certificate of Incorporation, no dividend shall be paid to holders of common stock (other than dividends of common
  stock) unless a dividend of equal or greater amount (calculated on an on an as-converted basis) is
  paid to holders of Series&nbsp;A-2 preferred stock. In the event of a liquidation, dissolution or
  winding up of the Registrant, holders of the outstanding Series&nbsp;A-2 preferred stock will have a
  right to receive a return of their original purchase price plus declared but unpaid dividends for
  their shares of preferred stock, prior to and in preference of any distribution of assets of the
  Registrant to any holder of common stock. Under the terms of the outstanding Series&nbsp;A-2 preferred
  stock as set forth in the Certificate of Incorporation, a liquidation is deemed to include any situation in which (i)&nbsp;a single stockholder or
  group of affiliated stockholders, other than Genentech or its controlled affiliate, who would be
  required to file a Schedule&nbsp;13D under the Exchange Act, acquires or obtains the right to acquire
  voting stock of the Registrant so that its total holdings of such stock equal or exceed 50% of the
  then outstanding voting stock of the Registrant or (ii)&nbsp;any third party, other than Genentech or
  its controlled affiliate, acquires or obtains the right to acquire all or substantially all of the
  Registrant&#146;s assets.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<I>Other Rights. </I>There are no redemption or sinking fund provisions applicable to the
  Registrant&#146;s outstanding Series&nbsp;A-2 preferred stock.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<B><I>Amended and Restated Rights Agreement and Series&nbsp;X Junior Participating Preferred Stock</I></B>
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;A description of the rights issued under the Registrant&#146;s amended and restated rights
  agreement and of the registrant&#146;s Series&nbsp;X junior participating preferred stock reserved for
  issuance in connection with such amended and restated rights agreement is set forth in the
  Registrant&#146;s Registration Statement on Form 8-A/A filed with the Commission on July&nbsp;27, 2001, as
  amended by a Form&nbsp;8&#150;A/A filed with the
  </DIV>
  
  <P align="center" style="font-size: 10pt">4
  </DIV>
  
  <!-- PAGEBREAK -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">Commission on June&nbsp;25, 2003, and any amendment or report updating such description of the such
  preferred stock purchase rights, which documents are incorporated by reference into this document.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The Registrant&#146;s amended and restated rights agreement may have anti-take-over effects. The
  rights may cause substantial dilution to a person or group that attempts to acquire the Registrant.
  Accordingly, the existence of the rights may deter acquirors from making takeover proposals or
  tender offers.
  </DIV>
  <!-- link2 "Item&nbsp;5: Interests of Named Experts and Counsel" -->
  <DIV align="left"><A NAME="004"></A></DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 12pt"><B>Item&nbsp;5: Interests of Named Experts and Counsel</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The validity of the shares of common stock being registered by this Registration Statement has
  been passed upon by Skadden, Arps, Slate, Meagher &#038; Flom LLP.
  </DIV>
  <!-- link2 "Item&nbsp;6: Indemnification of Directors and Officers" -->
  <DIV align="left"><A NAME="005"></A></DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 12pt"><B>Item&nbsp;6: Indemnification of Directors and Officers</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The Certificate of Incorporation provides that
  a director of the Registrant shall not be personally liable to the Registrant or its stockholders
  for monetary damages for any breach of fiduciary duty as a director, except for liability for (i)
  any breach of the director&#146;s duty of loyalty to the Registrant or its stockholders; (ii)&nbsp;acts or
  omissions not in good faith or which involve intentional misconduct or a knowing violation of law;
  (iii)&nbsp;unlawful payments of dividends or unlawful stock repurchases or redemptions as provided in
  Section&nbsp;174 of the DGCL; or (iv)&nbsp;any transaction from which the director derived an improper
  personal benefit. This provision has no effect on any non-monetary remedies that may be available
  to the Registrant or its stockholders, nor does it relieve the Registrant or its officers or
  directors from compliance with federal or state securities laws.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The Certificate of Incorporation provides that
  to the fullest extent permitted by applicable law, the Registrant is authorized to provide
  indemnification of, and advancement of expenses to, such agents and any other persons to which
  Delaware law permits the Registrant to provide indemnification though bylaw provisions, agreements
  with such agents or other persons, vote of stockholders or disinterested directors or otherwise, in
  excess of the indemnification and advancement otherwise permitted by Section&nbsp;145 of the DGCL,
  subject only to limits created by applicable Delaware law, with respect to actions for breach of
  duty to the Registrant, its stockholders, and others.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The Registrant&#146;s Bylaws provide that the Registrant shall indemnify its directors to the
  fullest extent authorized under Delaware law, and that the Board of Directors of the Registrant
  shall have the power, on behalf of the Registrant, to indemnify any other person made party to any
  action, suit, or proceeding by reason of the fact that he, his testator or intestate, is or was an
  officer or employee of the Registrant. The Registrant&#146;s Bylaws also provide that, except in
  specified circumstances, expenses incurred by a director of the registrant in defending a civil or
  criminal action, suit or proceeding by reason of the fact that he or she is or was a director of
  the Registrant (or was serving at the Registrant&#146;s request as a director or officer of another
  corporation) shall be paid by the Registrant in advance of the final disposition of such action,
  suit or proceeding.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Section&nbsp;145 of the DGCL provides that a corporation has the power to indemnify a director,
  officer, employee or agent of the corporation and certain other persons serving at the request of
  the corporation in related capacities against amounts paid and expenses incurred in connection with
  an action or proceeding to which he is or is threatened to be made a party by reason of such
  position, if such person shall have acted in good faith and in a manner he reasonably believed to
  be in or not opposed to the best interests of the corporation, and, in any criminal proceeding, if
  such person had no reasonable cause to
  </DIV>
  
  <P align="center" style="font-size: 10pt">5
  </DIV>
  
  <!-- PAGEBREAK -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">believe his conduct was unlawful; provided that, in the case
  of actions brought by or in the right of the
  corporation, no indemnification shall be made with respect to any matter as to which such
  person shall have been adjudged to be liable to the corporation unless and only to the extent that
  the adjudicating court determines that such indemnification is proper under the circumstances.
  Section&nbsp;145 of the DGCL also provides that a corporation shall indemnify a director or officer of
  the corporation to the extent he or she has been successful on the merits or otherwise in defense
  of any such action, suit or proceeding, for expenses reasonably incurred in connection with such
  action, suit or proceeding.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The Registrant has secured insurance on behalf of directors, officers and employees of the
  Registrant and its subsidiaries for liability arising out of certain claims which may be made
  against them, whether or not the Registrant would have the power to indemnify them against such
  liability under the DGCL.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;In addition to indemnification provided for in its Bylaws, the Registrant has entered into
  agreements with certain of its directors and officers to indemnify them for, among other things,
  certain expenses (including attorneys&#146; fees), judgments, fines and settlement amounts reasonably
  incurred by them in any action or proceeding, including any action by or in the right of the
  Registrant, to which they are a party by reason of the fact that they were or are a director,
  officer, employee or agent of the Registrant or of any other company or enterprise to which the
  person provides such services at the Registrant&#146;s request.
  </DIV>
  <!-- link2 "Item&nbsp;7: Exemption from Registration Claimed" -->
  <DIV align="left"><A NAME="006"></A></DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 12pt"><B>Item&nbsp;7: Exemption from Registration Claimed</B>
  </DIV>
  
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="100%">&nbsp;</TD>
  </TR>
  <!-- End Table Head -->
  <!-- Begin Table Body -->
  <TR valign="bottom">
      <TD valign="top"><DIV style="margin-left:0px; text-indent:-0px">Not applicable.</DIV></TD>
  </TR>
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  <!-- link2 "Item&nbsp;8: Exhibits" -->
  <DIV align="left"><A NAME="007"></A></DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 12pt"><B>Item&nbsp;8: Exhibits</B>
  </DIV>
  
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="1%">&nbsp;</TD>
      <TD width="4%">&nbsp;</TD>
      <TD width="3%">&nbsp;</TD>
      <TD width="1%">&nbsp;</TD>
      <TD width="3%">&nbsp;</TD>
      <TD width="4%">&nbsp;</TD>
      <TD width="88%">&nbsp;</TD>
  </TR>
  <TR style="font-size: 8pt" valign="bottom">
      <TD nowrap align="left" colspan="5" style="border-bottom: 1px solid #000000">Exhibit Number</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="left" style="border-bottom: 1px solid #000000">Description</TD>
  </TR>
  
  <!-- End Table Head -->
  <!-- Begin Table Body -->
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.1 </TD>
      <TD nowrap valign="top">(1)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Amended and Restated Certificate of Incorporation, dated December&nbsp;1, 1999</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.2 </TD>
      <TD nowrap valign="top">(1)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Certificate of Amendment of Amended and Restated Certificate of
  Incorporation, dated May&nbsp;21, 2001</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.3 </TD>
      <TD nowrap valign="top">(1)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Certificate increasing the number of authorized shares of Series&nbsp;X junior
  participating preferred stock, dated July&nbsp;26, 2001</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.4 </TD>
      <TD nowrap valign="top">(1)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Certificate of Amendment of Amended and Restated Certificate of
  Incorporation, dated November&nbsp;12, 2003</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.5 </TD>
      <TD nowrap valign="top">(1)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Bylaws</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.6 </TD>
      <TD nowrap valign="top">(1)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Amendment to Bylaws, dated December&nbsp;21, 2001</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.7 </TD>
      <TD nowrap valign="top">(1)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Amendment to Bylaws, dated November&nbsp;12, 2003</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.3 </TD>
      <TD nowrap valign="top">(1)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Specimen Certificate representing shares of common stock (including legend
  under Amended and Restated Rights Agreement, dated as of July&nbsp;26, 2001,
  between the Registrant and Mellon Investor Services LLC, as amended)</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.5 </TD>
      <TD nowrap valign="top">(2)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Amended and Restated Rights Agreement, dated as of July&nbsp;26, 2001, between
  the Registrant and Mellon Investor Services LLC</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.6 </TD>
      <TD nowrap valign="top">(3)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Amendment No.&nbsp;1 to Amended and Restated Rights Agreement, dated as of June
  20, 2003, between the Registrant and Mellon Investor Services LLC</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  
  <P align="center" style="font-size: 10pt">6
  </DIV>
  
  <!-- PAGEBREAK -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="1%">&nbsp;</TD>
      <TD width="4%">&nbsp;</TD>
      <TD width="3%">&nbsp;</TD>
      <TD width="1%">&nbsp;</TD>
      <TD width="3%">&nbsp;</TD>
      <TD width="4%">&nbsp;</TD>
      <TD width="88%">&nbsp;</TD>
  </TR>
  <TR style="font-size: 8pt" valign="bottom">
      <TD nowrap align="left" colspan="5" style="border-bottom: 1px solid #000000">Exhibit Number</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="left" style="border-bottom: 1px solid #000000">Description</TD>
  </TR>
  
  <!-- End Table Head -->
  <!-- Begin Table Body -->
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.6</TD>
      <TD nowrap valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Reference is made to Exhibits 4.1, 4.2, 4.3 and 4.4 for a description of
  the rights, preferences and privileges of the Registrant&#146;s Series&nbsp;A
  preferred stock and Series&nbsp;X junior participating preferred stock</TD>
  </TR>
  
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.7</TD>
      <TD nowrap valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Form of rights certificate (attached as Exhibit&nbsp;B to the Amended and
  Restated Rights Agreement filed as Exhibit&nbsp;4.5 hereto)</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">5.1</TD>
      <TD nowrap valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Opinion of Skadden, Arps, Slate, Meagher &#038; Flom LLP</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">23.1</TD>
      <TD nowrap valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Consent of Independent Registered Public Accounting Firm&#151;PricewaterhouseCoopers LLP</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">23.2</TD>
      <TD nowrap valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Consent of Independent Registered Public Accounting Firm&#151;KPMG LLP</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">23.3</TD>
      <TD nowrap valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Consent of Skadden, Arps, Slate, Meagher &#038; Flom LLP (included in Exhibit
  5.1)</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">24.1</TD>
      <TD nowrap valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Powers of Attorney (included in signature page to Registration Statement)</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">99.1 </TD>
      <TD nowrap valign="top">(4)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Biogen Idec Inc. 2005 Omnibus Equity Plan</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">99.2 </TD>
      <TD nowrap valign="top">(4)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Biogen Idec Inc. 1995 Employee Stock Purchase Plan, as amended and restated</TD>
  </TR>
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  
  
  <DIV align="left">
  <DIV style="font-size: 3pt; margin-top: 16pt; width: 18%; border-top: 1px solid #000000">&nbsp;</DIV>
  </DIV>
  
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  <TR>
      <TD width="3%"></TD>
      <TD width="1%"></TD>
      <TD width="96"></TD>
  </TR>
  
  <TR valign="top">
      <TD nowrap align="left">(1)</TD>
      <TD>&nbsp;</TD>
      <TD>Incorporated by reference to an exhibit filed with the Registrant&#146;s Annual Report on Form
  10-K for the year ended December&nbsp;31, 2003 filed with the Commission on March&nbsp;10, 2004.</TD>
  </TR>
  
  <TR style="font-size: 3pt"><TD>&nbsp;</TD></TR>
  
  <TR valign="top">
      <TD nowrap align="left">(2)</TD>
      <TD>&nbsp;</TD>
      <TD>Incorporated by reference to an exhibit filed with the Registrant&#146;s Registration Statement on
  Form 8-A/A, dated July&nbsp;26, 2001, filed with the Commission on July&nbsp;27, 2001.</TD>
  </TR>
  
  <TR style="font-size: 3pt"><TD>&nbsp;</TD></TR>
  
  <TR valign="top">
      <TD nowrap align="left">(3)</TD>
      <TD>&nbsp;</TD>
      <TD>Incorporated by reference to an exhibit filed with the Registrant&#146;s Current Report on Form
  8-K filed with the Commission on June&nbsp;23, 2003.</TD>
  </TR>
  
  <TR style="font-size: 3pt"><TD>&nbsp;</TD></TR>
  
  <TR valign="top">
      <TD nowrap align="left">(4)</TD>
      <TD>&nbsp;</TD>
      <TD>Incorporated by reference to an appendix filed with the Company&#146;s Definitive Proxy Statement
  on Schedule&nbsp;14A filed with the Commission on April&nbsp;15, 2005.</TD>
  </TR>
  
  </TABLE>
  
  
  <!-- link2 "Item&nbsp;9: Undertakings" -->
  <DIV align="left"><A NAME="008"></A></DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 12pt"><B>Item&nbsp;9: Undertakings</B>
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">(a)&nbsp;The undersigned Registrant hereby undertakes:
  </DIV>
  
  
  <DIV style="margin-top: 6pt">
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="2%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(1)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>To file, during any period in which offers or sales are being made, a
  post-effective amendment to this Registration Statement:</TD>
  </TR>
  
  </TABLE>
  </DIV>
  
  <DIV style="margin-top: 6pt">
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="6%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(i)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>To include any prospectus required by Section&nbsp;10(a)(3) of the
  Securities Act;</TD>
  </TR>
  
  <TR>
      <TD style="font-size: 6pt">&nbsp;</TD>
  </TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="6%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(ii)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>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,
  represent a fundamental change in the information set forth in the Registration
  Statement; and</TD>
  </TR>
  
  <TR>
      <TD style="font-size: 6pt">&nbsp;</TD>
  </TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="6%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(iii)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>To include any material information with respect to the plan
  of distribution not previously disclosed in the Registration Statement or any
  material change to such information in the Registration Statement;</TD>
  </TR>
  
  <TR>
      <TD style="font-size: 6pt">&nbsp;</TD>
  </TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="6%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left"><I>&nbsp;</I></TD>
      <TD width="1%"><I>&nbsp;</I></TD>
      <TD><I>provided, however</I>, that paragraphs (a)(1)(i) and (a)(1)(ii) of this section do not
  apply if the information required to be included in a post-effective amendment by
  those paragraphs is contained in periodic reports filed with or furnished to the
  Commission by the </TD>
  </TR>
  
  </TABLE>
  </DIV>
  <P align="center" style="font-size: 10pt">7
  </DIV>
  
  <!-- PAGEBREAK -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  
  <DIV style="margin-top: 6pt"><TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  <TR valign="top" style="font-size: 10pt; color: #textcolor#; background: #bgcolor#">
      <TD width="6%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">&nbsp;</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>Registrant pursuant to Section&nbsp;13 or Section 15(d) of the Exchange
  Act that are incorporated by reference in the Registration Statement;</TD>
  </TR>
  
  </TABLE>
  </DIV>
  
  <DIV style="margin-top: 6pt">
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="2%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(2)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>That, for the purpose of determining any liability under the Securities Act,
  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; and</TD>
  </TR>
  
  <TR>
      <TD style="font-size: 6pt">&nbsp;</TD>
  </TR><TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="2%" style="background: transparent">&nbsp;</TD>
      <TD width="3%" nowrap align="left">(3)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>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.</TD>
  </TR>
  
  </TABLE>
  </DIV>
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">(b)&nbsp;The undersigned Registrant hereby undertakes that, for purposes of determining any liability
  under the Securities Act, each filing of the Registrant&#146;s annual report pursuant to Section 13(a)
  or Section 15(d) of the Exchange Act (and, where applicable, each filing of an employee benefit
  plan&#146;s annual report pursuant to Section 15(d) of the Exchange Act) 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.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">(c)&nbsp;Insofar as indemnification for liabilities arising under the Securities Act may be permitted to
  directors, officers and controlling persons of the Registrant pursuant to the foregoing provisions,
  or otherwise, the Registrant has been advised that in the opinion of the Commission such
  indemnification is against public policy as expressed in the Securities 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 Securities Act and will be
  governed by the final adjudication of such issue.
  </DIV>
  
  
  
  <P align="center" style="font-size: 10pt">8
  </DIV>
  
  <!-- PAGEBREAK -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  
  
  <!-- link1 "SIGNATURES" -->
  <DIV align="left"><A NAME="009"></A></DIV>
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>SIGNATURES</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Pursuant to the requirements of the Securities Act, 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 Cambridge, State of Massachusetts on
  this 15th day of September,
  2005.
  </DIV>
  
  <TABLE width="100%" border="0" cellspacing="0" cellpadding="0" style="font-size: 10pt">
  <TR>
      <TD width="48%">&nbsp;</TD>
      <TD width="1%">&nbsp;</TD>
      <TD width="1%">&nbsp;</TD>
      <TD width="35%">&nbsp;</TD>
      <TD width="15%">&nbsp;</TD>
  </TR>
  <TR>
      <TD valign="top" align="left">&nbsp;</TD>
      <TD colspan="3" align="left">BIOGEN IDEC INC.<BR>
  &nbsp;</TD>
      <TD>&nbsp;</TD>
  </TR><TR>
      <TD align="left">&nbsp;</TD>
      <TD valign="top">By:&nbsp;&nbsp;</TD>
      <TD colspan="2" style="border-bottom: 1px solid #000000" align="left">
  /s/ Peter N. Kellogg&nbsp;</TD>
      <TD>&nbsp;</TD>
  </TR><TR>
      <TD align="left">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD colspan="2" align="left">Peter N. Kellogg&nbsp;</TD>
      <TD>&nbsp;</TD>
  </TR><TR>
      <TD align="left">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD colspan="2" align="left">Executive Vice President, Finance and
  Chief Financial Officer&nbsp;</TD>
      <TD>&nbsp;</TD>
  </TR>
  <TR>
      <TD colspan="5">&nbsp;</TD>
  </TR>
  </TABLE>
  <!-- link1 "POWER OF ATTORNEY" -->
  <DIV align="left"><A NAME="010"></A></DIV>
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>POWER OF ATTORNEY</B>
  </DIV>
  
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes
  and appoints James C. Mullen and Peter N. Kellogg, and each of them individually, as his or her
  true and lawful attorneys-in-fact and agents, with full power of substitution and resubstitution,
  for him or her and in his or her name, place and stead, in any and all capacities, to sign any and
  all amendments (including post-effective amendments) to this Registration Statement on Form S-8,
  and to file the same, with all exhibits thereto, and other documents in connection therewith, with
  the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each
  of them, full power and authority to do and perform each and every act and thing requisite and
  necessary to be done in connection therewith, as fully to all intents and purposes as he or she
  might or could do in person, hereby ratifying and confirming all that said attorney-in-facts and
  agents, or either of them, or their or his substitute or substitutes, may lawfully do or cause to
  be done by virtue hereof.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Pursuant to the requirements of the Securities Act, this Registration Statement has been
  signed by the following persons in the capacities and on the dates indicated.
  </DIV>
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="30%">&nbsp;</TD>
      <TD width="5%">&nbsp;</TD>
      <TD width="30%">&nbsp;</TD>
      <TD width="5%">&nbsp;</TD>
      <TD width="30%">&nbsp;</TD>
  </TR>
  <TR style="font-size: 8pt" valign="bottom">
      <TD nowrap align="left"><B>Signature</B></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>Title</B></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>Date</B></TD>
  </TR>
  
  <!-- End Table Head -->
  <!-- Begin Table Body -->
  <TR valign="bottom">
      <TD align="center" nowrap valign="top">/s/ James C. Mullen<BR>
  <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>
  James C. Mullen</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">
  Chief Executive Officer,
  President and Director
  (Principal Executive Officer)
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="bottom">September 15, 2005</TD>
  </TR>
  <TR valign="bottom" style="padding-top: 1em">
      <TD align="center" nowrap valign="top">/s/ Peter N. Kellogg<BR>
  <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>
  Peter N. Kellogg</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">
  Executive Vice President,
  Finance and Chief Financial
  Officer (Principal Financial
  Officer and Principal
  Accounting Officer)
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="bottom">September 15, 2005</TD>
  </TR>
  <TR valign="bottom" style="padding-top: 1em">
      <TD align="center" nowrap valign="top">/s/ William H. Rastetter, Ph.D.<BR>
  <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>
  William H. Rastetter, Ph.D.</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">
  Executive Chairman and Director
  </TD>
  
      <TD>&nbsp;</TD>
      <TD align="center" valign="bottom">September 15, 2005</TD>
  </TR>
  <TR valign="bottom" style="padding-top: 1em">
      <TD align="center" nowrap valign="top">/s/ Alan Belzer<BR>
  <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>
  Alan Belzer</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">
  Director
  </TD>
  
      <TD>&nbsp;</TD>
      <TD align="center" valign="bottom">September 15, 2005</TD>
  </TR>
  <TR valign="bottom" style="padding-top: 1em">
      <TD align="center" nowrap valign="top">/s/ Lawrence C. Best<BR>
  <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>
  Lawrence C. Best</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">
  Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="bottom">September 15, 2005</TD>
  </TR>
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  
  <P align="center" style="font-size: 10pt">&nbsp;
  </DIV>
  
  <!-- PAGEBREAK -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="30%">&nbsp;</TD>
      <TD width="5%">&nbsp;</TD>
      <TD width="30%">&nbsp;</TD>
      <TD width="5%">&nbsp;</TD>
      <TD width="30%">&nbsp;</TD>
  </TR>
  <TR style="font-size: 8pt" valign="bottom">
      <TD nowrap align="left"><B>Signature</B></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>Title</B></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>Date</B></TD>
  </TR>
  
  <!-- End Table Head -->
  <!-- Begin Table Body -->
  <TR valign="bottom" style="padding-top: 1em">
      <TD align="center" nowrap valign="top">/s/ Alan B. Glassberg, M.D.<BR>
  <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>
  Alan B. Glassberg, M.D.</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">
  Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="bottom">September 15, 2005</TD>
  </TR>
  <TR valign="bottom" style="padding-top: 1em">
      <TD align="center" nowrap valign="top">/s/ Mary L. Good, Ph.D.<BR>
  <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>
  Mary L. Good, Ph.D.</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">
  Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="bottom">September 15, 2005</TD>
  </TR>
  <TR valign="bottom" style="padding-top: 1em">
      <TD align="center" nowrap valign="top">/s/ Thomas F. Keller, Ph.D.<BR>
  <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>
  Thomas F. Keller, Ph.D.</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">
  Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="bottom">September 15, 2005</TD>
  </TR>
  <TR valign="bottom" style="padding-top: 1em">
      <TD align="center" nowrap valign="top">/s/ Robert W. Pangia<BR>
  <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>
  Robert W. Pangia</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">
  Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="bottom">September 15, 2005</TD>
  </TR>
  <TR valign="bottom" style="padding-top: 1em">
      <TD align="center" nowrap valign="top">/s/ Bruce R. Ross<BR>
  <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>
  Bruce R. Ross</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">
  Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="bottom">September 15, 2005</TD>
  </TR>
  <TR valign="bottom" style="padding-top: 1em">
      <TD align="center" nowrap valign="top">/s/ Lynn Schenk<BR>
  <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>
  Lynn Schenk</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">
  Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="bottom">September 15, 2005</TD>
  </TR>
  <TR valign="bottom" style="padding-top: 1em">
      <TD align="center" nowrap valign="top">/s/ Phillip A. Sharp, Ph.D.<BR>
  <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>
  Phillip A. Sharp, Ph.D.</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">
  Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="bottom">September 15, 2005</TD>
  </TR>
  <TR valign="bottom" style="padding-top: 1em">
      <TD align="center" nowrap valign="top">/s/ William D. Young<BR>
  <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>
  William D. Young</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">
  Director
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="bottom">September 15, 2005</TD>
  </TR>
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  
  <P align="center" style="font-size: 10pt">&nbsp;
  </DIV>
  
  <!-- PAGEBREAK -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>EXHIBIT INDEX</B>
  </DIV>
  
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="1%">&nbsp;</TD>
      <TD width="4%">&nbsp;</TD>
      <TD width="3%">&nbsp;</TD>
      <TD width="1%">&nbsp;</TD>
      <TD width="3%">&nbsp;</TD>
      <TD width="4%">&nbsp;</TD>
      <TD width="88%">&nbsp;</TD>
  </TR>
  <TR style="font-size: 8pt" valign="bottom">
      <TD nowrap align="left" colspan="5" style="border-bottom: 1px solid #000000">Exhibit Number</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="left" style="border-bottom: 1px solid #000000">Description</TD>
  </TR>
  
  <!-- End Table Head -->
  <!-- Begin Table Body -->
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.1 </TD>
      <TD nowrap valign="top">(1)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Amended and Restated Certificate of Incorporation, dated December&nbsp;1, 1999</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.2 </TD>
      <TD nowrap valign="top">(1)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Certificate of Amendment of Amended and Restated Certificate of
  Incorporation, dated May&nbsp;21, 2001</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.3 </TD>
      <TD nowrap valign="top">(1)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Certificate increasing the number of authorized shares of Series&nbsp;X junior
  participating preferred stock, dated July&nbsp;26, 2001</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.4 </TD>
      <TD nowrap valign="top">(1)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Certificate of Amendment of Amended and Restated Certificate of
  Incorporation, dated November&nbsp;12, 2003</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.5 </TD>
      <TD nowrap valign="top">(1)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Bylaws</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.6 </TD>
      <TD nowrap valign="top">(1)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Amendment to Bylaws, dated December&nbsp;21, 2001</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.7 </TD>
      <TD nowrap valign="top">(1)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Amendment to Bylaws, dated November&nbsp;12, 2003</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.3 </TD>
      <TD nowrap valign="top">(1)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Specimen Certificate representing shares of common stock (including legend
  under Amended and Restated Rights Agreement, dated as of July&nbsp;26, 2001,
  between the Registrant and Mellon Investor Services LLC, as amended)</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.5 </TD>
      <TD nowrap valign="top">(2)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Amended and Restated Rights Agreement, dated as of July&nbsp;26, 2001, between
  the Registrant and Mellon Investor Services LLC</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.6 </TD>
      <TD nowrap valign="top">(3)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Amendment No.&nbsp;1 to Amended and Restated Rights Agreement, dated as of June
  20, 2003, between the Registrant and Mellon Investor Services LLC</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.6</TD>
      <TD nowrap valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Reference is made to Exhibits 4.1, 4.2, 4.3 and 4.4 for a description of the
  rights, preferences and privileges of the Registrant&#146;s Series&nbsp;A preferred
  stock and Series&nbsp;X junior participating preferred stock</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">4.7</TD>
      <TD nowrap valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Form of rights certificate (attached as Exhibit&nbsp;B to the Amended and
  Restated Rights Agreement filed as Exhibit&nbsp;4.5 hereto)</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">5.1</TD>
      <TD nowrap valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Opinion of Skadden, Arps, Slate, Meagher &#038; Flom LLP</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">23.1</TD>
      <TD nowrap valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Consent of Independent Registered Public Accounting Firm&#151;PricewaterhouseCoopers LLP</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">23.2</TD>
      <TD nowrap valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Consent of Independent Registered Public Accounting Firm&#151;KPMG LLP</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">23.3</TD>
      <TD nowrap valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Consent of Skadden, Arps, Slate, Meagher &#038; Flom LLP (included in Exhibit&nbsp;5.1)</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">24.1</TD>
      <TD nowrap valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Powers of Attorney (included in signature page to Registration Statement)</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">99.1 </TD>
      <TD nowrap valign="top">(4)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Biogen Idec Inc. 2005 Omnibus Equity Plan</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;</DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">&nbsp;
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">99.2 </TD>
      <TD nowrap valign="top">(4)</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Biogen Idec Inc. 1995 Employee Stock Purchase Plan, as amended and restated</TD>
  </TR>
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  <DIV style="font-size: 3pt; margin-top: 16pt; width: 18%; border-top: 1px solid #000000">&nbsp;</DIV>
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      <TD width="3%"></TD>
      <TD width="1%"></TD>
      <TD width="96"></TD>
  </TR>
  
  <TR valign="top">
      <TD nowrap align="left">(1)</TD>
      <TD>&nbsp;</TD>
      <TD>Incorporated by reference to an exhibit filed with the Registrant&#146;s Annual Report on Form
  10-K for the year ended December&nbsp;31, 2003 filed with the Commission on March&nbsp;10, 2004.</TD>
  </TR>
  
  <TR style="font-size: 3pt"><TD>&nbsp;</TD></TR>
  
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      <TD nowrap align="left">(2)</TD>
      <TD>&nbsp;</TD>
      <TD>Incorporated by reference to an exhibit filed with the Registrant&#146;s Registration Statement on
  Form 8-A/A, dated July&nbsp;26, 2001, filed with the Commission on July&nbsp;27, 2001.</TD>
  </TR>
  
  <TR style="font-size: 3pt"><TD>&nbsp;</TD></TR>
  
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      <TD nowrap align="left">(3)</TD>
      <TD>&nbsp;</TD>
      <TD>Incorporated by reference to an exhibit filed with the Registrant&#146;s Current Report on Form
  8-K filed with the Commission on June&nbsp;23, 2003.</TD>
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  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  
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      <TD nowrap align="left">(4)</TD>
      <TD>&nbsp;</TD>
      <TD>Incorporated by reference to an appendix filed with the Registrant&#146;s Definitive Proxy
  Statement on Schedule&nbsp;14A filed with the Commission on April&nbsp;15, 2005.</TD>
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text: sv8
  Table of Contents
  As
  filed with the United States Securities and Exchange Commission on
  September 15, 2005
  Registration No. 333-________
  UNITED STATES SECURITIES AND EXCHANGE COMMISSION
  Washington, D.C. 20549
  FORM S-8
  REGISTRATION STATEMENT
  UNDER THE SECURITIES ACT OF 1933
  BIOGEN IDEC INC.
  (Exact name of registrant as specified in its charter)
  Delaware
  33-0112644
  (State or other jurisdiction of
  incorporation or organization)
  (I.R.S. Employer Identification No.)
  14 Cambridge Center
  Cambridge, Massachusetts 02142
  (Address of Principal Executive Offices) (Zip Code)
  Biogen Idec Inc. 2005 Omnibus Equity Plan
  Biogen Idec Inc. 1995 Employee Stock Purchase Plan
  (Full title of the plan)
  Peter N. Kellogg
  Executive Vice President, Finance and Chief Financial Officer
  Biogen Idec Inc.
  14 Cambridge Center
  Cambridge, Massachusetts 02142
  (617) 679-2000
  (Name, address and telephone number, including area code, of agent for service)
  CALCULATION OF REGISTRATION FEE
  Amount to Be
  Proposed Maximum
  Proposed Maximum
  Amount of
  Registered
  Offering Price per
  Aggregate Offering
  Registration Fee
  Title of Securities To Be Registered
  (1)(2)(3)
  Share (4)
  Price (4)
  (5)
  Common stock, $0.0005 par value per
  share (including the associated rights
  to purchase Series X junior
  participating preferred stock)(2)
  20,857,448 shares
  $41.04
  $855,989,666
  $93,915
  (1)
  Includes 18,857,448 shares issuable under the Biogen Idec Inc. 2005 Omnibus Equity Plan (the
  "2005 Plan") and 2,000,000 shares issuable under the Biogen Idec Inc. 1995 Employee Stock
  Purchase Plan, as amended and restated (the "ESPP"). The aggregate number of shares to be
  registered is subject to adjustment by reason of stock splits, stock dividends and other
  events pursuant to the terms of the 2005 Plan or the ESPP, as applicable. Accordingly,
  pursuant to Rule 416 under the Securities Act of 1933, as amended (the "Securities Act"), this
  Registration Statement covers, in addition to the number of shares of common stock shown in
  the table above, an indeterminate number of shares of the Registrant's common stock which may
  be subject to grant or otherwise issuable by operation of the provisions of the 2005 Plan or
  the ESPP governing such adjustments.
  (2)
  This Registration Statement also covers the rights to purchase shares of the Registrant's
  Series X junior participating preferred stock issuable in accordance with the Amended and
  Restated Rights Agreement, dated as of July 26, 2001, between the Registrant and Mellon
  Investor Services LLC, as amended. These rights initially are attached to and trade
  with the Registrant's common stock. The value attributed to such rights, if any, is
  reflected in the market price of the Registrant's common stock.
  (3)
  The Registrant is carrying forward to this Registration Statement 3,857,448 shares of the
  Registrant's common stock (including the associated rights to purchase Series X junior
  participating preferred stock) previously registered under its Registration Statement on Form
  S-8 (SEC File No. 333-110432).
  (4)
  Estimated pursuant to Rule 457(h) of the Securities Act, solely for the purpose of
  calculating the registration fee, on the basis of the average of the high and low selling
  prices of the Registrant's common stock as reported on the
  Nasdaq National Market on September 14, 2005. The filing fee
  payable is $100,750. Of this amount, the Registrant offsets
  $6,836 in fees previously paid with respect to the shares of common stock carried forward to
  this Registration Statement from Registration Statement on Form S-8 (SEC File No. 333-110432).
  The remaining amount of fees payable of $93,915 has been transmitted as of the date hereof.
  (5)
  The registration fee has been calculated pursuant to Section 6(b) of the Securities Act by
  multiplying .0001177 by the proposed maximum aggregate offering price (as computed in
  accordance with Rule 457 under the Securities Act solely for the purpose of determining the
  registration fee of the securities registered hereby).
  TABLE OF CONTENTS
  PART I
  PART II
  Item 3: Incorporation of Documents by Reference
  Item 4: Description of Securities
  Item 5: Interests of Named Experts and Counsel
  Item 6: Indemnification of Directors and Officers
  Item 7: Exemption from Registration Claimed
  Item 8: Exhibits
  Item 9: Undertakings
  SIGNATURES
  POWER OF ATTORNEY
  EX-5.1 OPINION OF SKADDEN, ARPS, SLATE, MEAGHER & FLOM LLP
  EX-23.1 CONSENT OF PRICEWATERHOUSECOOPERS LLP
  EX-23.2 CONSENT OF KPMG LLP
  Table of Contents
  PART I
  INFORMATION REQUIRED IN THE SECTION 10(A) PROSPECTUS
  The documents containing the information specified in Part I have been sent or given to
  employees as specified by Rule 428(b)(1). Such documents are not being filed with the Securities
  and Exchange Commission (the "Commission") either as part of this Registration Statement or as
  prospectuses or prospectus supplements pursuant to Rule 424. Such documents and the documents
  incorporated by reference in this Registration Statement pursuant to Item 3 of Part II of this
  Form, taken together, constitute a prospectus that meets the requirements of Section 10(a) of the
  Securities Act.
  PART II
  INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
  Item 3: Incorporation of Documents by Reference
  The Registrant hereby incorporates by reference into this Registration Statement the following
  documents, which have been previously filed by the Registrant with the Commission:
  (1)
  Registrant's Annual Report on Form 10-K for the year ended December 31, 2004
  filed with the Commission on March 31, 2005;
  (2)
  Registrant's Quarterly Report on Form 10-Q for the quarter ended March 31, 2005
  filed with the Commission on April 29, 2005;
  (3)
  Registrant's Quarterly Report on Form 10-Q for the quarter ended June 30, 2005
  filed with the Commission on July 27, 2005;
  (4)
  Registrant's Current Reports on Form 8-K filed with the Commission on January
  6, 2005, February 22, 2005, February 24, 2005, March 3, 2005, March 7, 2005, March 23,
  2005, April 1, 2005 (as to Items 8.01 and 9.01 only), May 3, 2005, May 11, 2005, June
  6, 2005, June 16, 2005, August 11, 2005 and
  September 13, 2005;
  (5)
  Registrant's Definitive Proxy Statement on Form DEF14A filed on April 15, 2005;
  (6)
  The description of the Registrant's common stock contained in the Registration
  Statement on Form 8-B filed with the Commission on June 2, 1997, including any
  amendment or report updating such description of the common stock; and
  (7)
  The description of the Registrant's preferred stock purchase rights contained
  in its Registration Statement on Form 8-A filed with the Commission on August 1, 1997,
  as amended by Form 8-A/A filed with the Commission on July 27, 2001 and Form 8–A/A
  filed with the Commission on June 25, 2003, including any amendment or report updating
  such description of the such preferred stock purchase rights.
  Until such time that a post-effective amendment to this Registration Statement has been filed
  which indicates that all securities offered hereby have been sold or which deregisters all
  securities remaining unsold at the time of such amendment, all documents subsequently filed by the
  Registrant pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Securities Exchange Act of 1934,
  as amended (the
  2
  Table of Contents
  "Exchange Act"), shall be deemed to be incorporated by reference in this Registration
  Statement and to be a part hereof from the date of filing of such documents.
  Any statement contained herein or in a document incorporated or deemed to be incorporated by
  reference herein shall be deemed to be modified or superseded for purposes of this Registration
  Statement to the extent that a statement contained herein or in any subsequently filed document
  which is also deemed to be incorporated by reference herein modifies or supersedes such statement.
  Any such statement so modified or superseded shall not be deemed, except as so modified or
  superseded, to constitute a part of this Registration Statement.
  Item 4: Description of Securities
  The class of securities being offered by this Registration Statement is registered under
  Section 12 of the Securities Exchange Act of 1934. The Registrant provides the below description
  to update the description of its common stock contained in its Registration Statement on Form 8-B
  filed with the Commission on June 2, 1997.
  Under
  the Registrant's Amended and Restated Certificate of
  Incorporation, as amended (the "Certificate of
  Incorporation"), the Registrant's
  authorized capital stock consists of 1,000,000,000 shares of common stock, $0.0005 par value per
  share, and 8,000,000 shares of preferred stock, $0.001 par value per share. As of June 30, 2005,
  1,750,000 shares of preferred stock were designated as Series A preferred stock and 1,000,000
  shares of preferred stock were reserved for issuance as Series X junior participating preferred
  stock in connection with the Registrant's preferred stock purchase rights described in the
  Registrant's Registration Statement on Form 8-A filed with the Commission on August 1, 1997, as
  amended by Form 8-A/A filed with the Commission on July 27, 2001 and Form 8–A/A filed with the
  Commission on June 25, 2003, including any amendment or report updating such description of the
  such preferred stock purchase rights. As of June 30, 2005, there were outstanding 337,836,891
  shares of common stock and 8,221 shares of Series A-2 preferred stock.
  Registrant Common Stock
  Voting Rights
  . Each holder of common stock is entitled to one vote for each share of common
  stock held of record on the applicable record date on all matters submitted to a vote of
  stockholders.
  Dividend Rights; Rights Upon Liquidation
  . The holders of common stock are entitled to
  receive, from funds legally available for the payment thereof, dividends when and as declared by
  resolution of the Registrant's board of directors, subject to any preferential dividend rights
  granted to the holders of any outstanding preferred stock. In the event of a liquidation,
  dissolution or winding up of the Registrant, each share of common stock is entitled to share pro
  rata in any distribution of the Registrant's assets after payment or providing for the payment of
  liabilities and the liquidation preference of any outstanding preferred stock.
  Preemptive Rights
  . Holders of common stock have no preemptive rights to purchase, subscribe
  for or otherwise acquire any unissued or treasury shares or other securities.
  Transfer Agent and Registrar
  . The transfer agent and registrar for common stock is Equiserve
  Trust Company, N.A.
  Description of Preferred Stock
  3
  Table of Contents
  Pursuant
  to the Certificate of Incorporation, the
  Registrant's board of directors is authorized to issue up to an aggregate of 8,000,000 shares of
  preferred stock in one or more series and to fix the rights, preferences, privileges and
  restrictions, including the dividend rights, conversion rights, voting rights, rights and terms of
  redemption, redemption price or prices, liquidation preferences and the number of shares
  constituting any series or the designations of such series, without any further vote or action by
  the stockholders. The issuance of preferred stock in certain circumstances may have the effect of
  delaying, deferring or preventing a change of control of the Registrant without further actions of
  the stockholders. The issuance of preferred stock with voting and conversion rights may adversely
  affect the voting power of the holders of common stock, including the loss of voting control to
  others.
  Preferred Stock Outstanding
  . As of June 30, 2005, there were 8,221 shares of Series A-2
  preferred stock outstanding, all of which are owned by Genentech, Inc., and no other shares of
  preferred stock outstanding. The outstanding shares of Series A-2 preferred stock are duly
  authorized, validly issued, fully paid and non-assessable.
  Voting Rights.
  None of the Series A-2 preferred stock outstanding has voting rights, except
  as may be required by the Delaware General Corporation Law (the "DGCL").
  Conversion.
  Each share of Series A-2 preferred stock is convertible at any time into 60
  shares of the Registrant's common stock. The outstanding shares of Series A-2 preferred stock
  automatically convert into common stock in the event that a person or entity other than Genentech
  or its affiliate acquires such shares. The conversion rate of the Series A-2 preferred stock is
  subject to adjustment for certain stock splits, stock dividends, combinations and other events.
  Dividend Rights; Rights Upon Liquidation.
  Under the terms of the outstanding Series A-2
  preferred stock as set forth in the Certificate of Incorporation, no dividend shall be paid to holders of common stock (other than dividends of common
  stock) unless a dividend of equal or greater amount (calculated on an on an as-converted basis) is
  paid to holders of Series A-2 preferred stock. In the event of a liquidation, dissolution or
  winding up of the Registrant, holders of the outstanding Series A-2 preferred stock will have a
  right to receive a return of their original purchase price plus declared but unpaid dividends for
  their shares of preferred stock, prior to and in preference of any distribution of assets of the
  Registrant to any holder of common stock. Under the terms of the outstanding Series A-2 preferred
  stock as set forth in the Certificate of Incorporation, a liquidation is deemed to include any situation in which (i) a single stockholder or
  group of affiliated stockholders, other than Genentech or its controlled affiliate, who would be
  required to file a Schedule 13D under the Exchange Act, acquires or obtains the right to acquire
  voting stock of the Registrant so that its total holdings of such stock equal or exceed 50% of the
  then outstanding voting stock of the Registrant or (ii) any third party, other than Genentech or
  its controlled affiliate, acquires or obtains the right to acquire all or substantially all of the
  Registrant's assets.
  Other Rights.
  There are no redemption or sinking fund provisions applicable to the
  Registrant's outstanding Series A-2 preferred stock.
  Amended and Restated Rights Agreement and Series X Junior Participating Preferred Stock
  A description of the rights issued under the Registrant's amended and restated rights
  agreement and of the registrant's Series X junior participating preferred stock reserved for
  issuance in connection with such amended and restated rights agreement is set forth in the
  Registrant's Registration Statement on Form 8-A/A filed with the Commission on July 27, 2001, as
  amended by a Form 8–A/A filed with the
  4
  Table of Contents
  Commission on June 25, 2003, and any amendment or report updating such description of the such
  preferred stock purchase rights, which documents are incorporated by reference into this document.
  The Registrant's amended and restated rights agreement may have anti-take-over effects. The
  rights may cause substantial dilution to a person or group that attempts to acquire the Registrant.
  Accordingly, the existence of the rights may deter acquirors from making takeover proposals or
  tender offers.
  Item 5: Interests of Named Experts and Counsel
  The validity of the shares of common stock being registered by this Registration Statement has
  been passed upon by Skadden, Arps, Slate, Meagher & Flom LLP.
  Item 6: Indemnification of Directors and Officers
  The Certificate of Incorporation provides that
  a director of the Registrant shall not be personally liable to the Registrant or its stockholders
  for monetary damages for any breach of fiduciary duty as a director, except for liability for (i)
  any breach of the director's duty of loyalty to the Registrant or its stockholders; (ii) acts or
  omissions not in good faith or which involve intentional misconduct or a knowing violation of law;
  (iii) unlawful payments of dividends or unlawful stock repurchases or redemptions as provided in
  Section 174 of the DGCL; or (iv) any transaction from which the director derived an improper
  personal benefit. This provision has no effect on any non-monetary remedies that may be available
  to the Registrant or its stockholders, nor does it relieve the Registrant or its officers or
  directors from compliance with federal or state securities laws.
  The Certificate of Incorporation provides that
  to the fullest extent permitted by applicable law, the Registrant is authorized to provide
  indemnification of, and advancement of expenses to, such agents and any other persons to which
  Delaware law permits the Registrant to provide indemnification though bylaw provisions, agreements
  with such agents or other persons, vote of stockholders or disinterested directors or otherwise, in
  excess of the indemnification and advancement otherwise permitted by Section 145 of the DGCL,
  subject only to limits created by applicable Delaware law, with respect to actions for breach of
  duty to the Registrant, its stockholders, and others.
  The Registrant's Bylaws provide that the Registrant shall indemnify its directors to the
  fullest extent authorized under Delaware law, and that the Board of Directors of the Registrant
  shall have the power, on behalf of the Registrant, to indemnify any other person made party to any
  action, suit, or proceeding by reason of the fact that he, his testator or intestate, is or was an
  officer or employee of the Registrant. The Registrant's Bylaws also provide that, except in
  specified circumstances, expenses incurred by a director of the registrant in defending a civil or
  criminal action, suit or proceeding by reason of the fact that he or she is or was a director of
  the Registrant (or was serving at the Registrant's request as a director or officer of another
  corporation) shall be paid by the Registrant in advance of the final disposition of such action,
  suit or proceeding.
  Section 145 of the DGCL provides that a corporation has the power to indemnify a director,
  officer, employee or agent of the corporation and certain other persons serving at the request of
  the corporation in related capacities against amounts paid and expenses incurred in connection with
  an action or proceeding to which he is or is threatened to be made a party by reason of such
  position, if such person shall have acted in good faith and in a manner he reasonably believed to
  be in or not opposed to the best interests of the corporation, and, in any criminal proceeding, if
  such person had no reasonable cause to
  5
  Table of Contents
  believe his conduct was unlawful; provided that, in the case
  of actions brought by or in the right of the
  corporation, no indemnification shall be made with respect to any matter as to which such
  person shall have been adjudged to be liable to the corporation unless and only to the extent that
  the adjudicating court determines that such indemnification is proper under the circumstances.
  Section 145 of the DGCL also provides that a corporation shall indemnify a director or officer of
  the corporation to the extent he or she has been successful on the merits or otherwise in defense
  of any such action, suit or proceeding, for expenses reasonably incurred in connection with such
  action, suit or proceeding.
  The Registrant has secured insurance on behalf of directors, officers and employees of the
  Registrant and its subsidiaries for liability arising out of certain claims which may be made
  against them, whether or not the Registrant would have the power to indemnify them against such
  liability under the DGCL.
  In addition to indemnification provided for in its Bylaws, the Registrant has entered into
  agreements with certain of its directors and officers to indemnify them for, among other things,
  certain expenses (including attorneys' fees), judgments, fines and settlement amounts reasonably
  incurred by them in any action or proceeding, including any action by or in the right of the
  Registrant, to which they are a party by reason of the fact that they were or are a director,
  officer, employee or agent of the Registrant or of any other company or enterprise to which the
  person provides such services at the Registrant's request.
  Item 7: Exemption from Registration Claimed
  Not applicable.
  Item 8: Exhibits
  Exhibit Number
  Description
  4.1
  (1)
  Amended and Restated Certificate of Incorporation, dated December 1, 1999
  4.2
  (1)
  Certificate of Amendment of Amended and Restated Certificate of
  Incorporation, dated May 21, 2001
  4.3
  (1)
  Certificate increasing the number of authorized shares of Series X junior
  participating preferred stock, dated July 26, 2001
  4.4
  (1)
  Certificate of Amendment of Amended and Restated Certificate of
  Incorporation, dated November 12, 2003
  4.5
  (1)
  Bylaws
  4.6
  (1)
  Amendment to Bylaws, dated December 21, 2001
  4.7
  (1)
  Amendment to Bylaws, dated November 12, 2003
  4.3
  (1)
  Specimen Certificate representing shares of common stock (including legend
  under Amended and Restated Rights Agreement, dated as of July 26, 2001,
  between the Registrant and Mellon Investor Services LLC, as amended)
  4.5
  (2)
  Amended and Restated Rights Agreement, dated as of July 26, 2001, between
  the Registrant and Mellon Investor Services LLC
  4.6
  (3)
  Amendment No. 1 to Amended and Restated Rights Agreement, dated as of June
  20, 2003, between the Registrant and Mellon Investor Services LLC
  6
  Table of Contents
  Exhibit Number
  Description
  4.6
  Reference is made to Exhibits 4.1, 4.2, 4.3 and 4.4 for a description of
  the rights, preferences and privileges of the Registrant's Series A
  preferred stock and Series X junior participating preferred stock
  4.7
  Form of rights certificate (attached as Exhibit B to the Amended and
  Restated Rights Agreement filed as Exhibit 4.5 hereto)
  5.1
  Opinion of Skadden, Arps, Slate, Meagher & Flom LLP
  23.1
  Consent of Independent Registered Public Accounting Firm—PricewaterhouseCoopers LLP
  23.2
  Consent of Independent Registered Public Accounting Firm—KPMG LLP
  23.3
  Consent of Skadden, Arps, Slate, Meagher & Flom LLP (included in Exhibit
  5.1)
  24.1
  Powers of Attorney (included in signature page to Registration Statement)
  99.1
  (4)
  Biogen Idec Inc. 2005 Omnibus Equity Plan
  99.2
  (4)
  Biogen Idec Inc. 1995 Employee Stock Purchase Plan, as amended and restated
  (1)
  Incorporated by reference to an exhibit filed with the Registrant's Annual Report on Form
  10-K for the year ended December 31, 2003 filed with the Commission on March 10, 2004.
  (2)
  Incorporated by reference to an exhibit filed with the Registrant's Registration Statement on
  Form 8-A/A, dated July 26, 2001, filed with the Commission on July 27, 2001.
  (3)
  Incorporated by reference to an exhibit filed with the Registrant's Current Report on Form
  8-K filed with the Commission on June 23, 2003.
  (4)
  Incorporated by reference to an appendix filed with the Company's Definitive Proxy Statement
  on Schedule 14A filed with the Commission on April 15, 2005.
  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;
  (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,
  represent a fundamental change in the information set forth in the Registration
  Statement; and
  (iii)
  To include any material information with respect to the plan
  of distribution not previously disclosed in the Registration Statement or any
  material change to such information in the Registration Statement;
  provided, however
  , that paragraphs (a)(1)(i) and (a)(1)(ii) of this section do not
  apply if the information required to be included in a post-effective amendment by
  those paragraphs is contained in periodic reports filed with or furnished to the
  Commission by the
  7
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  Registrant pursuant to Section 13 or Section 15(d) of the Exchange
  Act that are incorporated by reference in the Registration Statement;
  (2)
  That, for the purpose of determining any liability under the Securities Act,
  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; and
  (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, each filing of the Registrant's annual report pursuant to Section 13(a)
  or Section 15(d) of the Exchange Act (and, where applicable, each filing of an employee benefit
  plan's annual report pursuant to Section 15(d) of the Exchange Act) 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 may be permitted to
  directors, officers and controlling persons of the Registrant pursuant to the foregoing provisions,
  or otherwise, the Registrant has been advised that in the opinion of the Commission such
  indemnification is against public policy as expressed in the Securities 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 Securities Act and will be
  governed by the final adjudication of such issue.
  8
  Table of Contents
  SIGNATURES
  Pursuant to the requirements of the Securities Act, 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 Cambridge, State of Massachusetts on
  this 15th day of September,
  2005.
  BIOGEN IDEC INC.
  By:
  /s/ Peter N. Kellogg
  Peter N. Kellogg
  Executive Vice President, Finance and
  Chief Financial Officer
  POWER OF ATTORNEY
  KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes
  and appoints James C. Mullen and Peter N. Kellogg, and each of them individually, as his or her
  true and lawful attorneys-in-fact and agents, with full power of substitution and resubstitution,
  for him or her and in his or her name, place and stead, in any and all capacities, to sign any and
  all amendments (including post-effective amendments) to this Registration Statement on Form S-8,
  and to file the same, with all exhibits thereto, and other documents in connection therewith, with
  the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each
  of them, full power and authority to do and perform each and every act and thing requisite and
  necessary to be done in connection therewith, as fully to all intents and purposes as he or she
  might or could do in person, hereby ratifying and confirming all that said attorney-in-facts and
  agents, or either of them, or their or his substitute or substitutes, may lawfully do or cause to
  be done by virtue hereof.
  Pursuant to the requirements of the Securities Act, this Registration Statement has been
  signed by the following persons in the capacities and on the dates indicated.
  Signature
  Title
  Date
  /s/ James C. Mullen
  James C. Mullen
  Chief Executive Officer,
  President and Director
  (Principal Executive Officer)
  September 15, 2005
  /s/ Peter N. Kellogg
  Peter N. Kellogg
  Executive Vice President,
  Finance and Chief Financial
  Officer (Principal Financial
  Officer and Principal
  Accounting Officer)
  September 15, 2005
  /s/ William H. Rastetter, Ph.D.
  William H. Rastetter, Ph.D.
  Executive Chairman and Director
  September 15, 2005
  /s/ Alan Belzer
  Alan Belzer
  Director
  September 15, 2005
  /s/ Lawrence C. Best
  Lawrence C. Best
  Director
  September 15, 2005
  Table of Contents
  Signature
  Title
  Date
  /s/ Alan B. Glassberg, M.D.
  Alan B. Glassberg, M.D.
  Director
  September 15, 2005
  /s/ Mary L. Good, Ph.D.
  Mary L. Good, Ph.D.
  Director
  September 15, 2005
  /s/ Thomas F. Keller, Ph.D.
  Thomas F. Keller, Ph.D.
  Director
  September 15, 2005
  /s/ Robert W. Pangia
  Robert W. Pangia
  Director
  September 15, 2005
  /s/ Bruce R. Ross
  Bruce R. Ross
  Director
  September 15, 2005
  /s/ Lynn Schenk
  Lynn Schenk
  Director
  September 15, 2005
  /s/ Phillip A. Sharp, Ph.D.
  Phillip A. Sharp, Ph.D.
  Director
  September 15, 2005
  /s/ William D. Young
  William D. Young
  Director
  September 15, 2005
  Table of Contents
  EXHIBIT INDEX
  Exhibit Number
  Description
  4.1
  (1)
  Amended and Restated Certificate of Incorporation, dated December 1, 1999
  4.2
  (1)
  Certificate of Amendment of Amended and Restated Certificate of
  Incorporation, dated May 21, 2001
  4.3
  (1)
  Certificate increasing the number of authorized shares of Series X junior
  participating preferred stock, dated July 26, 2001
  4.4
  (1)
  Certificate of Amendment of Amended and Restated Certificate of
  Incorporation, dated November 12, 2003
  4.5
  (1)
  Bylaws
  4.6
  (1)
  Amendment to Bylaws, dated December 21, 2001
  4.7
  (1)
  Amendment to Bylaws, dated November 12, 2003
  4.3
  (1)
  Specimen Certificate representing shares of common stock (including legend
  under Amended and Restated Rights Agreement, dated as of July 26, 2001,
  between the Registrant and Mellon Investor Services LLC, as amended)
  4.5
  (2)
  Amended and Restated Rights Agreement, dated as of July 26, 2001, between
  the Registrant and Mellon Investor Services LLC
  4.6
  (3)
  Amendment No. 1 to Amended and Restated Rights Agreement, dated as of June
  20, 2003, between the Registrant and Mellon Investor Services LLC
  4.6
  Reference is made to Exhibits 4.1, 4.2, 4.3 and 4.4 for a description of the
  rights, preferences and privileges of the Registrant's Series A preferred
  stock and Series X junior participating preferred stock
  4.7
  Form of rights certificate (attached as Exhibit B to the Amended and
  Restated Rights Agreement filed as Exhibit 4.5 hereto)
  5.1
  Opinion of Skadden, Arps, Slate, Meagher & Flom LLP
  23.1
  Consent of Independent Registered Public Accounting Firm—PricewaterhouseCoopers LLP
  23.2
  Consent of Independent Registered Public Accounting Firm—KPMG LLP
  23.3
  Consent of Skadden, Arps, Slate, Meagher & Flom LLP (included in Exhibit 5.1)
  24.1
  Powers of Attorney (included in signature page to Registration Statement)
  99.1
  (4)
  Biogen Idec Inc. 2005 Omnibus Equity Plan
  99.2
  (4)
  Biogen Idec Inc. 1995 Employee Stock Purchase Plan, as amended and restated
  (1)
  Incorporated by reference to an exhibit filed with the Registrant's Annual Report on Form
  10-K for the year ended December 31, 2003 filed with the Commission on March 10, 2004.
  (2)
  Incorporated by reference to an exhibit filed with the Registrant's Registration Statement on
  Form 8-A/A, dated July 26, 2001, filed with the Commission on July 27, 2001.
  (3)
  Incorporated by reference to an exhibit filed with the Registrant's Current Report on Form
  8-K filed with the Commission on June 23, 2003.
  Table of Contents
  (4)
  Incorporated by reference to an appendix filed with the Registrant's Definitive Proxy
  Statement on Schedule 14A filed with the Commission on April 15, 2005.