Ownership Submission
FORM 3
 UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

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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(Print or Type Responses)
1. Name and Address of Reporting Person *
  Gagnon Robert E.
 2. Date of Event Requiring Statement (Month/Day/Year)
11/03/2010		 3. Issuer Name and Ticker or Trading Symbol
BIOGEN IDEC INC. [BIIB]
(Last)
(First)
(Middle)
BIOGEN IDEC INC., 133 BOSTON POST ROAD		 4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director _____ 10% Owner
__X__ Officer (give title below) _____ Other (specify below)
Chief Acct Officer VP & Contol
 5. If Amendment, Date Original Filed(Month/Day/Year)
(Street)

WESTON, MA 02493		 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 Beneficially Owned
1.Title of Security
(Instr. 4)		 2. Amount of Securities Beneficially Owned
(Instr. 4)		 3. Ownership Form: Direct (D) or Indirect (I)
(Instr. 5)		 4. Nature of Indirect Beneficial Ownership
(Instr. 5)
Common Stock 12,777
D
 

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly. SEC 1473 (7-02)
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Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 4)		 2. Date Exercisable and Expiration Date
(Month/Day/Year)		 3. Title and Amount of Securities Underlying Derivative Security
(Instr. 4)		 4. Conversion or Exercise Price of Derivative Security 5. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 5)		 6. Nature of Indirect Beneficial Ownership
(Instr. 5)
Date Exercisable Expiration Date Title Amount or Number of Shares
Stock Option (Right to Buy)   (1) 10/31/2015 Common Stock 1,700 $ 40.63 D  
Stock Option (Right to Buy)   (2) 10/01/2018 Common Stock 3,110 $ 49.59 D  
Stock Option (Right to Buy)   (3) 02/24/2019 Common Stock 4,215 $ 49.65 D  
Restricted Stock Unit   (4) 02/23/2014 Common Stock 4,892 $ 0 D  

Reporting Owners

Reporting Owner Name / Address Relationships
Director 10% Owner Officer Other
Gagnon Robert E.
BIOGEN IDEC INC.
133 BOSTON POST ROAD
WESTON, MA 02493		       Chief Acct Officer VP & Contol  

Signatures

Aras Lapinskas, Attorney in Fact for Robert E. Gagnon 11/10/2010
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 5(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).
(1) The stock options become exercisable in four (4) equal annual installments commencing one year after the grant date of 10/31/2005.
(2) The stock options become exercisable in four (4) equal annual installments commencing one year after the grant date of 10/01/2008.
(3) The stock options become exercisable in four (4) equal annual installments commencing one year after the grant date of 02/24/09.
(4) The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 150% of the number of shares at target payout. One-fourth of these RSUs are eligible to vest on each of the first four anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen Idec common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the average 60 calendar-day closing stock price ending on the vesting date divided by the average 60 calendar-day closing stock price on the grant date]).

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