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

FORM 8-K

CURRENT REPORT

Date of Report (Date of earliest event reported): October 27, 2004

Biogen Idec Inc.

Registrant’s telephone number, including area code: (617) 679-2000

Not Applicable
(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

o  Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

o  Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

o  Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

o  Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Table of Contents

ITEM 2.02      Results of Operations and Financial Condition.

     The press release attached as Exhibit 99.1 includes information with respect to the following: (a) the Registrant’s adjusted non-GAAP earnings per share and net income for the third quarter and the first nine months of 2004, and (b) the Registrant’s adjusted pro forma non-GAAP earnings per share, net income and revenues for the third quarter and the first nine months of 2003. These are non-GAAP financial measures.

     The non-GAAP financial measures for the third quarter and the first nine months of 2004 exclude non-operational and unusual activities and transactions. The non-GAAP financial measures for the third quarter and the first nine months of 2003 include revenue and expenses from the former Biogen, Inc. and exclude non-operational and unusual activities and transactions of the former Biogen, Inc. and IDEC Pharmaceuticals Corporation.

     Management believes that the non-GAAP financial measures provide useful information to investors. In particular, management believes that they allow investors to monitor and evaluate the Registrant’s ongoing operating results and trends and gain a better understanding of the Registrant’s business, period-to-period performance, and prospects for future performance.

     This press release is being furnished pursuant to Item 2.02 of this Current Report on Form 8-K and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934 (the “Exchange Act”) or otherwise subject to the liabilities of that Section, nor shall such documents be deemed incorporated by reference in any filing under the Securities Act of 1933 or the Exchange Act.

SIGNATURES

     Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Date:  October 27, 2004

EXHIBIT INDEX

Media Contact:
Amy Ryan
Associate Director, Public Affairs
Biogen Idec
Tel: (617) 914-6524

Investment Community Contact:
Elizabeth Woo
Senior Director, Investor Relations
Biogen Idec
Tel: (617) 679-2812

FOR IMMEDIATE RELEASE

Biogen Idec Reports Third Quarter 2004 Results

Cambridge, MA, October 27, 2004 — Biogen Idec Inc. (NASDAQ: BIIB), the world’s third largest biotech company with leading products and capabilities in oncology and immunology, today reported its third quarter 2004 results.

Third Quarter Highlights

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Page 2 Biogen Idec Reports Third Quarter 2004 Earnings

“Since we completed our merger transaction approximately one year ago, Biogen Idec has delivered on its promise,” said James Mullen, Biogen Idec’s Chief Executive Officer. “I applaud the organization for the smooth and rapid integration. We’ve hit our major financial goals, the pipeline has advanced both through in-house efforts and business development deals, and we are on the verge of launching our next product.”

Financial Performance

On an adjusted non-GAAP basis, Biogen Idec reported net income was $132 million in the third quarter of 2004 (Q3 2003: $123 million). Adjusted non-GAAP EPS was $0.37 for the third quarter of 2004 (Q3 2003: $0.35).

Adjusted non-GAAP EPS and net income for the third quarter of 2004 excludes merger-related accounting impacts, such as amortization of intangibles, impairment of intangibles, inventory step up, and other merger-related charges, and other non-operating charges. Adjusted pro forma non-GAAP EPS and net income for the third quarter of 2003 include revenue and expenses from the former Biogen, Inc. from July 1 to September 30, 2003 but excludes other non-operating charges of the former Biogen, Inc. and IDEC Pharmaceuticals Corporation. These adjustments, expenses, and non-operating charges are itemized on the attached reconciliation tables.

On a reported basis, calculated in accordance with U.S. generally accepted accounting principles (GAAP), Biogen Idec reported net income of $37 million (or EPS of $0.10) in the third quarter of 2004. The difference between adjusted non-GAAP net income and EPS and GAAP net income and EPS in the third quarter was primarily due to $112 million of non-cash merger-related accounting impacts and $13 million write-down of certain investments.

Revenue Performance

Third quarter revenues of AVONEX, Biogen Idec’s therapy for patients with relapsing forms of multiple sclerosis, increased 16% to $346 million (adjusted pro forma Q3 2003: $298 million).

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U.S. sales were $224 million (adjusted pro forma Q3 2003: $204 million). International sales were $122 million (adjusted pro forma Q3 2003: $94 million); in local currency, sales grew 21%.

Revenues for the third quarter of 2004 included $160 million from Biogen Idec’s joint business arrangement with Genentech, Inc. related to RITUXAN, a treatment for certain B-cell non-Hodgkin’s lymphomas that Biogen Idec co-promotes in the U.S. with Genentech (Q3 2003: $134 million). All U.S. sales of RITUXAN are recognized by Genentech, and Biogen Idec records its share of the pretax co-promotion profits on a quarterly basis. U.S. net sales of RITUXAN in the third quarter of 2004, as recorded by Genentech, were $393 million (Q3 2003: $354 million).

Revenues of ZEVALIN® (ibritumomab tiuxetan), Biogen Idec’s radioimmunotherapeutic agent, were $5 million in the third quarter of 2004 (Q3 2003: $4 million).

Revenues of AMEVIVE® (alefacept), Biogen Idec’s treatment for moderate-to-severe psoriasis, were $8 million in the third quarter of 2004 (Q3 2003: $12 million).

Royalties were $24 million in the third quarter (adjusted pro forma Q3 2003: $29 million).

Share Repurchase Program

Biogen Idec announced that its Board of Directors has authorized the repurchase of up to 20 million shares of its common stock. The repurchased stock will provide the Company with treasury shares for general corporate purposes, such as stock to be issued under employee stock option and stock purchase plans. The share buyback will be largely funded through operating cash flow and will be accretive to EPS.

William Rastetter, Biogen Idec’s Executive Chairman, said, “This share repurchase plan underscores the belief of management and the Board of Directors that our common stock represents an attractive investment for the Company, based on our well-defined strategy and our prospects for future growth. Given our strong anticipated operating cash flow, we do not expect this program to restrict our strategic flexibility.”

The Company currently has approximately 334 million shares of common stock outstanding.

Recent Highlights

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Conference Call and Webcast

The Company’s earnings conference call for the third quarter will be broadcast via the internet at 5:00 p.m. ET on October 27, 2004, and will be accessible through the investor relations section of Biogen Idec’s homepage, http://www.biogenidec.com.

About Biogen Idec

Biogen Idec creates new standards of care in oncology and immunology. As a global leader in the development, manufacturing, and commercialization of novel therapies, Biogen Idec transforms scientific discoveries into advances in human healthcare. For product labeling, press releases and additional information about the company, please visit www.biogenidec.com.

Safe Harbor

This press release contains forward-looking statements regarding expected future financial results and plans for our development programs, including ANTEGREN.

These statements are based on the Company’s current beliefs and expectations. A number of risks and uncertainties could cause actual results to differ materially. For example, financial results, including future operating cash flow and overall prospects

Page 5 Biogen Idec Reports Third Quarter 2004 Earnings

for growth, may be affected by a number of factors, including any slowing of growth of the markets for AVONEX and RITUXAN, any change in market acceptance of these products in key markets worldwide, the extent to which the Company achieves market acceptance of its other products, the impact of reimbursement and pricing decisions related to the Company’s products, the impact of competitive products on the Company’s products, any material decreases in sales by licensees of products on which the Company receives royalties, the impact of litigation, any unanticipated increase in expenses, in-licensing and product opportunities, increase in costs related to development and commercialization of new products, including ANTEGREN, and any material issues, delays or failures related to the manufacturing or supply of the Company’s products.

Our long-term growth will depend on the successful development and commercialization of new products such as ANTEGREN. Drug development involves a high degree of risk. For example, our plans to launch ANTEGREN as a treatment for MS could be negatively affected if unexpected concerns arise from additional data or analysis, if regulatory authorities require additional information or further studies, or if we were to encounter other unexpected hurdles.

For more detailed information on the risks and uncertainties associated with these forward looking statements and the Company’s other activities see the periodic reports filed by the Company with the Securities and Exchange Commission. The Company does not undertake any obligation to publicly update any forward-looking statements, whether as a result of new information, future events, or otherwise.

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TABLE 1
Financial Results For The Third Quarter of 2004
Condensed Consolidated Statements Of Income — GAAP Basis
(in thousands, except per share amounts)

TABLE 2

TABLE 3

Condensed Consolidated Statements of Operations and Reconciliation of GAAP Earnings to Adjusted Pro-Forma Non-GAAP Earnings (In millions, except per share data)

The non-GAAP financial measures presented below are utilized by Biogen Idec management to gain an understanding of the comparative financial performance of the Company. Management believes that the non-GAAP financial measures are useful because they exclude those non-operational or unusual activities or transactions that are not necessarily relevant to understanding the trends of the Company or the prospects of future performance. Numbers may not foot due to rounding.

TABLE 4

Condensed Consolidated Statements of Operations and Reconciliation of GAAP Earnings to Adjusted Pro-Forma Non-GAAP Earnings (In millions, except per share data)

The non-GAAP financial measures presented below are utilized by Biogen Idec management to gain an understanding of the comparative financial performance of the Company. Management believes that the non-GAAP financial measures are useful because they exclude those non-operational or unusual activities or transactions that are not necessarily relevant to understanding the trends of the Company or the prospects of future performance. Numbers may not foot due to rounding.

Table 5

Biogen Idec Inc
Product Revenues for Third Quarter 2004
(in thousands)

The non-GAAP financial measures presented below are utilized by Biogen Idec management to gain an understanding of the comparative financial performance of the Company. Management believes that the non-GAAP financial measures are useful because they exclude those non-operational or unusual activities or transactions that are not necessarily relevant to understanding the trends of the Company or the prospects of future performance. Numbers may not foot due to rounding.