BIOGEN INC. — Director's Dealing 2012

Feb 3, 2012

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: BIOGEN IDEC INC. (BIIB)
CIK: 0000875045
Period of Report: 2012-02-01

Reporting Person: Clancy Paul J (Executive VP and CFO)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2012-02-01	Common Stock	M	13000	$43.50	Acquired	34168	Direct
2012-02-01	Common Stock	M	8400	$67.57	Acquired	42568	Direct
2012-02-01	Common Stock	S	13000	$120.00	Disposed	29568	Direct
2012-02-01	Common Stock	S	8400	$120.00	Disposed	21168	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2012-02-01	Stock Option (Right to Buy)	$43.50	M	13000	Disposed	2014-02-06	Common Stock (13000)	Direct
2012-02-01	Stock Option (Right to Buy)	$67.57	M	8400	Disposed	2015-02-17	Common Stock (8400)	Direct

Footnotes

F1: Exercise/sale pursuant to a trading plan intended to comply with Rule 10b5-1 of the Securities Exchange Act of 1934.

F2: This represents the weighted average price for shares sold at a range between $120.00 (low) and $120.01 (high).

F3: Full information regarding the number of shares sold at each separate price will be provided upon request by the SEC staff, the issuer, or a security holder of the issuer.

F4: The stock option becomes exercisable in four(4) equal annual installments, commencing one year after the grant date of 02/06/04.

F5: The stock option becomes exercisable in four (4) equal annual installments, commencing one year after the grant date of 02/17/05.