BIOGEN INC. - Director's Dealing 2011

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: BIOGEN IDEC INC. (BIIB)
CIK: 0000875045
Period of Report: 2011-04-13

Reporting Person: Cox John (EVP Pharmaceutical Oper & Tech)

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2011-04-13	Common Stock	M	3900	$67.57	Acquired	14253.0295	Direct
2011-04-13	Common Stock	M	7400	$49.31	Acquired	21653.0295	Direct
2011-04-13	Common Stock	M	17347	$60.56	Acquired	39000.0295	Direct
2011-04-13	Common Stock	M	7587	$49.65	Acquired	46587.0295	Direct
2011-04-13	Common Stock	S	36234	$80.00	Disposed	10353.0295	Direct

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2011-04-13	Stock Option (Right to Buy)	$67.57	M	3900	Disposed	2015-02-17	Common Stock (3900)	Direct
2011-04-13	Stock Option (Right to Buy)	$49.31	M	7400	Disposed	2017-02-12	Common Stock (7400)	Direct
2011-04-13	Stock Option (Right to Buy)	$60.56	M	17347	Disposed	2018-02-12	Common Stock (17347)	Direct
2011-04-13	Stock Option (Right to Buy)	$49.65	M	7587	Disposed	2019-02-24	Common Stock (7587)	Direct

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

F2: The stock options became exercisable in four (4) equal annual installments commencing one year after the grant date of 2/17/2005.

F3: The stock options vest in four (4) equal annual installments commencing one year after the grant date of 2/12/2007.

F4: The stock options vest in four (4) equal annual installments commencing one year after the grant date of 2/12/2008.

F5: The stock options vest in four (4) equal annual installments commencing one year after the grant date of 2/24/2009.