BIOGEN INC. — Director's Dealing 2011

Apr 1, 2011

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: BIOGEN IDEC INC. (BIIB)
CIK: 0000875045
Period of Report: 2011-03-31

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

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2011-03-31	Common Stock	M	2840	$43.50	Acquired	12658.0411	Direct
2011-03-31	Common Stock	S	2840	$73.00	Disposed	9818.0411	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2011-03-31	Stock Option (Right to Buy)	$43.50	M	2840	Disposed	2014-02-06	Common Stock (2840)	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: The stock options became exercisable in four (4) equal annual installments commencing on 12/31/2004.