SEC Form 4 
FORM 4	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
or Section 30(h) of the Investment Company Act of 1940 	  
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	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).			
1. Name and Address of Reporting Person*
BUCKNUM THOMAS J	

(Last)	(First)	(Middle)	
14 CAMBRIDGE CENTER	

(Street) 
CAMBRIDGE	MA	02142	

(City)	(State)	(Zip)	
	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. General Counsel, Sec.	
		
	3. Date of Earliest Transaction (Month/Day/Year)
11/12/2003 		
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) 
X	Form filed by One Reporting Person	
	Form filed by More than One Reporting Person	
	
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned	
1. Title of Security (Instr. 3) 	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	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				
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 (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	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 (Month/Day/Year)	7. Title and Amount of Securities Underlying Derivative Security (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: 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	$13.04 	11/12/2003		A		80,500		(1) 	04/22/2006	Common Stock	80,500	(2)	80,500	D		
1985 NQ Stock Option	$16.9 	11/12/2003		A		9,200		(3) 	12/06/2006	Common Stock	9,200	(2)	9,200	D		
1985 NQ Stock Option	$15.54 	11/12/2003		A		9,200		(4) 	12/12/2007	Common Stock	9,200	(2)	9,200	D		
1985 NQ Stock Option	$35.42 	11/12/2003		A		9,200		(5) 	12/11/2008	Common Stock	9,200	(2)	9,200	D		
1985 NQ Stock Option	$47.15 	11/12/2003		A		57,500		(6) 	06/10/2009	Common Stock	57,500	(2)	57,500	D		
1985 NQ Stock Option	$62.28 	11/12/2003		A		17,250		(7) 	12/09/2009	Common Stock	17,250	(2)	17,250	D		
1985 NQ Stock Option	$45.46 	11/12/2003		A		28,750		(8) 	12/15/2010	Common Stock	28,750	(2)	28,750	D		
1985 NQ Stock Option	$49.03 	11/12/2003		A		86,250		(9) 	12/14/2011	Common Stock	86,250	(2)	86,250	D		
1985 NQ Stock Option	$37.45 	11/12/2003		A		46,000		(10) 	12/06/2012	Common Stock	46,000	(2)	46,000	D		
Explanation of Responses:	
1. The stock option became exercisable in six (6) equal annual installments, commencing one year after the grant date of 04/22/96.	
2. In connection with 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"), 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).	
3. The stock option became exercisable in six (6) equal annual installments, commencing one year after the grant date of 12/06/96.	
4. The stock option became exercisable in five (5) equal annual installments, commencing one year after the grant date 12/12/97.	
5. The stock option became exercisable in five (5) equal annual installments, commencing one year after the grant date 12/11/98.	
6. The stock option became exercisable in five (5) equal annual installments, commencing one year after the grant date 06/10/99.	
7. The stock option became exercisable in five (5) equal annual installments, commencing one year after the grant date 12/09/99.	
8. The stock option became exercisable in five (5) equal annual installments, commencing one year after the grant date 12/15/00.	
9. The stock option became exercisable in four (4) equal annual installments, commencing one year after the grant date 12/14/01.	
10. The stock option became exercisable in four (4) equal annual installments, commencing one year after the grant date 12/06/02.	
	/s/ Thomas J. Bucknum	11/12/2003	
	** Signature of Reporting Person	Date	
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.	
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).	
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).	
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.	
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