Biogen Idec Completes Review of Strategic Alternatives

The Board of Directors of Biogen Idec Inc. (NASDAQ: BIIB) today
announced that, after completing a review of strategic alternatives to
maximize shareholder value, Biogen Idec will continue on its present
course as an independent Company.

On October 12, the Board announced the start of a process to
determine whether potential strategic interest on the part of major
pharmaceutical companies might result in superior value for
stockholders in the current environment. Biogen Idec, which was
represented by independent financial advisors Goldman Sachs & Co. and
Merrill Lynch & Co., conducted a comprehensive and thorough sale
process. At the conclusion of this process, Biogen Idec did not
receive any definitive offers to purchase the Company.

The Board emphasized that Biogen Idec´s business strategy is
working and generating strong operating and financial performance. The
Board noted that it is confident that continued execution of the
Company´s business plan will result in attractive value for
stockholders. As previously announced, Biogen Idec´s business plan is
focused on achieving a series of goals by year-end 2010:

-- 100,000 patients on TYSABRI(R) (natalizumab);

-- More than 40% of the Company´s revenue coming from its
International business;

-- Four new products and/or existing products launched in new
indications;

-- Six programs in late-stage clinical development; and,

-- Generating revenue growth at a 15% compound annual growth rate
(CAGR) and non-GAAP EPS at a 20% CAGR from 2007 through 2010.

The Company reiterated guidance for the full-year 2007, which was
first announced on July 24, in reporting its second-quarter financial
results.

GAAP EPS Reconciliation for 2010 Goals

On a reported basis, calculated in accordance with accounting
principles generally accepted in the U.S. (GAAP), the Company aims to
grow GAAP EPS from 2007 through 2010 at a 25% CAGR. The long-term
non-GAAP EPS goal excludes the impact of purchase accounting,
merger-related adjustments, stock option expense, and their related
tax effects. In order to reconcile long-term GAAP and non-GAAP EPS
figures, the Company has excluded the following items for the years
2008 through 2010 from our non-GAAP EPS goal provided above:

-- Purchase accounting charges, including amortization of
acquired intangible assets and IPR&D, estimated to be
$800-$840 million for already completed transactions;

-- Stock option expense due to FAS 123R is estimated to be in the
range of $80-$90 million;

-- Tax benefit of $220-$240 million related to the pre-tax
reconciling items.

Because the Company cannot predict with certainty the nature or
the amount of non-operating or unusual charges through 2010, it has
made no assumption regarding new purchase accounting charges in this
GAAP EPS goal. The Company may incur charges or realize income through
2010 that could cause actual results to vary from the goal.

Use of Non-GAAP Financial Measures

Our "non-GAAP EPS" financial measure is defined as reported, or
GAAP, EPS excluding, for the reasons discussed below, (1) purchase
accounting and merger-related adjustments and (2) stock option
expense. We believe it is important to share these non-GAAP financial
measures with shareholders as they: better represent the ongoing
economics of the business, reflect how we manage the business
internally and set operational goals, and form the basis of our
management incentive programs. Accordingly, we believe investors´
understanding of the Company´s financial performance is enhanced as a
result of our disclosing these non-GAAP financial measures. Non-GAAP
EPS should not be viewed in isolation or as a substitute for reported,
or GAAP, EPS.

Purchase accounting and merger-related adjustments - Non-GAAP EPS
excludes certain purchase accounting impacts such as those related to
the merger with Biogen, Inc. (the "Merger") and the acquisitions of
Fumapharm AG, Conforma Therapeutics and Syntonix Pharmaceuticals.
These charges relate to in-process research and development charges
incurred upon the payment of future milestones and incremental charges
related to the amortization of the acquired intangible assets.
Excluding these charges allows management and investors an alternative
view of our financial results "as if" the acquired intangible asset
had been developed internally rather than acquired and, therefore,
provides a supplemental measure of performance in which the Company´s
acquired intellectual property is treated in a comparable manner to
its internally developed intellectual property.

Stock option expense - Non-GAAP EPS excludes the impact of our
stock option expense recorded in accordance with SFAS No. 123R. We
believe that excluding the impact of expensing stock options better
reflects the recurring economic characteristics of our integrated
business. We do include the P&L impact of restricted stock awards and
cash incentives in our non-GAAP results.

About Biogen Idec

Biogen Idec creates new standards of care in therapeutic areas
with high unmet medical needs. Founded in 1978, Biogen Idec is a
global leader in the discovery, development, manufacturing, and
commercialization of innovative therapies. Patients in more than 90
countries benefit from Biogen Idec´s significant products that address
diseases such as lymphoma, multiple sclerosis, and rheumatoid
arthritis. 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 about our
expected revenues, earnings, cash flows, product sales, product
development and other matters. Forward-looking statements are subject
to risks and uncertainties that could cause actual results to differ
materially from that which we expect. Important factors that could
cause our actual results to differ include our continued dependence on
our two principal products, AVONEX(R) (Interferon beta-1a) and
RITUXAN(R) (rituximab), the uncertainty of success in commercializing
other products including TYSABRI, the occurrence of adverse safety
events with our products, the failure to execute our growth strategy
successfully or to compete effectively in our markets, our dependence
on collaborations over which we may not always have full control,
possible adverse impact of government regulation and changes in the
availability of reimbursement for our products, problems with our
manufacturing processes and our reliance on third parties,
fluctuations in our operating results, our ability to protect our
intellectual property rights and the cost of doing so, the risks of
doing business internationally and the other risks and uncertainties
that are described in Item 1A Risk Factors in our most recent Form
10-Q filing with the SEC. These forward-looking statements speak only
as of the date of this press release, and we do not undertake any
obligation to publicly update any forward-looking statements, whether
as a result of new information, future events, or otherwise.