Sec Form 4 Filing - GREGOIRE SYLVIE L @ BIOGEN IDEC INC - 2003-11-12

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person GREGOIRE SYLVIE L 2. Issuer Name and Ticker or Trading Symbol BIOGEN IDEC INC [ BIIB] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) EVP, Bus. Dev & Program Mgmt. (Last) (First) (Middle) 14 CAMBRIDGE CENTER 3. Date of Earliest Transaction (MM/DD/YY) 11/12/2003 (Street) CAMBRIDGE, MA02142 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 11/12/2003 A 1,304 A 1,304 D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares 1985 NQ Stock Option $ 8.89 11/12/2003 A 16,100 ( 2 ) 01/02/2005 Common Stock 16,100 ( 3 ) 16,100 D 1985 NQ Stock Option $ 11.73 11/12/2003 A 11,040 ( 4 ) 09/22/2005 Common Stock 11,040 ( 3 ) 11,040 D 1985 NQ Stock Option $ 15.54 11/12/2003 A 4,600 ( 5 ) 12/12/2007 Common Stock 4,600 ( 3 ) 4,600 D 1985 NQ Stock Option $ 35.42 11/12/2003 A 46,000 ( 6 ) 12/11/2008 Common Stock 46,000 ( 3 ) 46,000 D 1985 NQ Stock Option $ 62.28 11/12/2003 A 34,500 ( 7 ) 12/09/2009 Common Sotck 34,500 ( 3 ) 34,500 D 1985 NQ Stock Option $ 45.46 11/12/2003 A 23,000 ( 8 ) 12/15/2010 Common Stock 23,000 ( 3 ) 23,000 D 1985 NQ Stock Option $ 49.61 11/12/2003 A 172,500 ( 9 ) 08/08/2011 Common Stock 172,500 ( 3 ) 172,500 D 1985 NQ Stock Option $ 37.45 11/12/2003 A 57,500 ( 10 ) 12/06/2012 Common Stock 57,500 ( 3 ) 57,500 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other GREGOIRE SYLVIE L 14 CAMBRIDGE CENTER CAMBRIDGE, MA02142 EVP, Bus. Dev & Program Mgmt. Signatures /s/ Sylvie L. Gregoire 11/14/2003 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The securities reported on this form were acquired by the reporting person in the merger of Bridges Merger Corporation, a wholly owned subsidiary of the Issuer, with and into Biogen, Inc. ("Biogen") effective on November 12, 2003 (the "Merger"). In the Merger, each share of common stock of Biogen, Inc. was exchanged for 1.15 (the "Exchange Ratio") shares of common stock of the Issuer. ( 2 )The stock option became exercisable in six (6) equal annual installments, commencing one year after the grant date of 01/02/95. ( 3 )In connection with the Merger, the Issuer assumed all options outstanding at the effective time of the merger under Biogen's existing stock option plans, including the options being reported on this form by the reporting person. Each such Biogen stock option is now exercisable for shares of the Issuer's common stock. The exercise price for each share of Issuer common stock is calculated by dividing the exercise price of the option immediately prior to the Merger for a share of Biogen common stock by the Exchange Ratio (rounded up to the nearest cent). The number of shares of Issuer common stock for which an assumed option may be exercised is calculated by multiplying the number of shares of Biogen common stock for which the option was exercisable immediately prior to the Merger by the Exchange Ratio (rounded down to the nearest whole share). ( 4 )The stock option became exercisable in six (6) equal annual installments, commencing one year after the grant date of 09/22/95. ( 5 )The stock option became exercisable in five (5) equal annual installments, commencing one year after the grant date of 12/12/97. ( 6 )The stock option becomes exercisable in five (5) equal annual installments, commencing one year after the grant date of 12/11/98. ( 7 )The stock option becomes exercisable in five (5) equal annual installments, commencing one year after the grant date of 12/09/99. ( 8 )The stock option becomes exercisable in five (5) equal annual installments, commencing one year after the grant date of 12/15/00. ( 9 )The stock option becomes exercisable in four (4) equal annual installments, commencing one year after the grant date of 08/08/01. ( 10 )The stock option becomes exercisable in four (4) equal annual installments, commencing one year after the grant date of 12/06/02.

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* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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