BIOGEN INC. — Director's Dealing 2013

May 31, 2013

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: BIOGEN IDEC INC. (BIIB)
CIK: 0000875045
Period of Report: 2013-05-29

Reporting Person: DENNER ALEXANDER J (Director)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2013-05-29	Common Stock	M	3000	$53.43	Acquired	7920	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2013-05-29	Stock Option (Right to Buy)	$53.43	M	3000	Disposed	2019-06-02	Common Stock (3000)	Direct

Footnotes

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

F2: Granted under one of the Issuer's stock option plans, in an exempt transaction under SEC Rule 16(b)-3(d).