BIOGEN INC. — Director's Dealing 2010

May 17, 2010

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: BIOGEN IDEC INC. (BIIB)
CIK: 0000875045
Period of Report: 2010-05-14

Reporting Person: DORSA CAROLINE (Director)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2010-05-14	Common Stock	P	1	$50.21	Acquired	1153	Direct
2010-05-14	Common Stock	P	94	$51.17	Acquired	1247	Direct
2010-05-14	Common Stock	P	100	$51.22	Acquired	1347	Direct

Footnotes

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