BIOGEN INC. — Director's Dealing 2010

Jun 10, 2010

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: BIOGEN IDEC INC. (BIIB)
CIK: 0000875045
Period of Report: 2010-06-08

Reporting Person: MULLEN JAMES C (Director, CEO & President)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2010-06-08	Common Stock	F	8253	$46.85	Disposed	122896	Direct
2010-06-08	Common Stock	F	13628	$46.85	Disposed	109268	Direct
2010-06-08	Common Stock	F	13765	$46.85	Disposed	95503	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2010-06-08	Non-qualified Stock Option (Right to Buy)	$49.03	D	249500	Disposed	2011-12-14	Common Stock (249500)	Direct
2010-06-08	Non-qualified Stock Option (Right to Buy)	$49.03	A	249500	Acquired	2011-12-14	Common Stock (249500)	Direct
2010-06-08	Stock Option (Right to Buy)	$67.57	D	325000	Disposed	2015-02-17	Common Stock (325000)	Direct
2010-06-08	Stock Option (Right to Buy)	$67.57	A	325000	Acquired	2015-02-17	Common Stock (325000)	Direct
2010-06-08	Stock Option (Right to Buy)	$44.59	D	120000	Disposed	2016-02-06	Common Stock (120000)	Direct
2010-06-08	Stock Option (Right to Buy)	$44.59	A	120000	Acquired	2016-02-06	Common Stock (120000)	Direct
2010-06-08	Stock Option (Right to Buy)	$49.17	D	210000	Disposed	2017-02-12	Common Stock (210000)	Direct
2010-06-08	Stock Option (Right to Buy)	$49.17	A	210000	Acquired	2017-02-12	Common Stock (210000)	Direct
2010-06-08	Stock Option (Right to Buy)	$63.24	D	166100	Disposed	2018-02-12	Common Stock (166100)	Direct
2010-06-08	Stock Option (Right to Buy)	$63.24	A	166100	Acquired	2018-02-12	Common Stock (166100)	Direct
2010-06-08	Stock Option (Right to Buy)	$50.55	D	131530	Disposed	2019-02-25	Common Stock (131530)	Direct
2010-06-08	Stock Option (Right to Buy)	$50.55	A	131530	Acquired	2019-02-25	Common Stock (131530)	Direct

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock	75000	Indirect

Footnotes

F1: The reported transactions represent amendments to the respective outstanding options (resulting in the deemed cancellation of the "old" option and the grant of a replacement option) extending their post-retirement exercise periods until June 8, 2013 or their expiration, whichever is earlier, pursuant to the Transition Agreement between Biogen Idec Inc. and James C. Mullen dated January 4, 2010. In addition, unvested outstanding options become fully exercisable upon retirement pursuant to the Transaction Agreement.

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

F3: The stock option became exercisable in four (4) equal annual installments, commencing one year after the grant date of 12/14/01.

F4: The stock option becomes exercisable in four (4) equal annual installments, commencing one year after the grant date of 02/17/05.

F5: The stock option becomes exercisable in four (4) equal annual installments, commencing one year after the grant date of 02/07/06.

F6: Granted under one of the Issuer's stock option plans, in an exempt transaction under SEC Rule 16(b)-3(d).

F7: The stock option becomes exercisable in four (4) equal annual installments, commencing one year after the grant date of 02/13/2007.

F8: The stock options become exercisable in four (4) equal annual installments, commencing one year after the grant date of 02/13/2008.

F9: The stock options become exercisable in four (4) equal annual installments commencing one year after the grant date of 02/25/09.