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	SEC FILE NUMBER
	0-19311
	CUSIP NUMBER
	09062X103

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 12b-25

NOTIFICATION OF LATE FILING

(Check one):		o  Form 10-K o  Form 20-F o  Form 11-K þ  Form 10-Q o  Form 10-D o  Form N-SAR o  Form N-CSR
		For Period Ended:		June 30, 2006
		o   Transition Report on Form 10-K
		o   Transition Report on Form 20-F
		o   Transition Report on Form 11-K
		o   Transition Report on Form 10-Q
		o   Transition Report on Form N-SAR
		For the Transition Period Ended:

If the notification relates to a portion of the filing checked above, identify the Item(s) to which the notification relates:

PART I — REGISTRANT INFORMATION

     Biogen Idec Inc.

Full Name of Registrant

Former Name if Applicable

     14 Cambridge Center

Address of Principal Executive Office (Street and Number)

     Cambridge, MA 02142

City, State and Zip Code

PART II — RULES 12b-25(b) AND (c)

If the subject report could not be filed without unreasonable effort or expense and the registrant seeks relief pursuant to Rule 12b-25(b), the following should be completed. (Check box if appropriate)

þ
			(a)		The reason described in reasonable detail in Part III of this form could not be eliminated without unreasonable effort or expense
			(b)		The subject annual report, semi-annual report, transition report on Form 10-K, Form 20-F, Form 11-K, Form N-SAR or Form N-CSR, or portion thereof, will be filed on or before the fifteenth calendar day following the prescribed due date; or the subject quarterly report or transition report on Form 10-Q or subject distribution report on Form 10-D, or portion thereof, will be filed on or before the fifth calendar day following the prescribed due date; and
			(c)		The accountant’s statement or other exhibit required by Rule 12b-25(c) has been attached if applicable.

PART III — NARRATIVE

State below in reasonable detail why Forms 10-K, 20-F, 11-K, 10-Q, 10-D, N-SAR, N-CSR, or the transition report or portion thereof, could not be filed within the prescribed time period.

The registrant was not able to timely file its quarterly report on Form 10-Q for the fiscal quarter ended June 30, 2006 because it had not completed the preparation of its financial statements for the period. On August 10, 2006, the registrant filed its quarterly report on Form 10-Q for the fiscal quarter ended June 30, 2006.

 
PART IV — OTHER INFORMATION

(1)

Name and telephone number of person to contact in regard to this notification

Peter N. Kellogg		617		679-2818
(Name)		(Area Code)		(Telephone Number)

(2)		Have all other periodic reports required under Section 13 or 15(d) of the Securities Exchange Act of 1934 or Section 30 of the Investment Company Act of 1940 during the preceding 12 months or for such shorter period that the registrant was required to file such report(s) been filed? If answer is no, identify report(s).
		Yes þ     No o

(3)		Is it anticipated that any significant change in results of operations from the corresponding period for the last fiscal year will be reflected by the earnings statements to be included in the subject report or portion thereof?
		Yes o     No þ
		If so, attach an explanation of the anticipated change, both narratively and quantitatively, and, if appropriate, state the reasons why a reasonable estimate of the results cannot be made.

(Name of Registrant as Specified in Charter)

has caused this notification to be signed on its behalf by the undersigned hereunto duly authorized.

Date:		August 10, 2006		By:		/s/ Peter N. Kellogg
						Peter N. Kellogg Executive Vice President, Finance and     Chief Financial Officer