Biogen Idec Launches New AVONEX(R) Nurse Services Program

Biogen Idec (NASDAQ: BIIB) announced today the national launch of
the new AVONEX(R) (Interferon beta-1a) Nurse Services program which is
designed to help people with multiple sclerosis (MS) as they begin and
continue treatment with AVONEX, the most prescribed treatment for
relapsing forms of MS worldwide. This new program is the latest
example of Biogen Idec's commitment to the MS community, which
includes offering the best support services to patients and
undertaking innovative research efforts to develop new therapeutic
options.

"As a person living with MS and as a nurse I can attest first-hand
that nurses play an important role in working closely with patients
and their healthcare providers in both the treatment and care of MS,"
said Marie Stallbaum, RN, BSN, a nurse with the AVONEX Nurse Services
Program. "Nurses in this program will be dedicated to helping MS
patients live the fullest and most active lives possible."

The AVONEX Nurse Services program will have registered nurses
covering the majority of the country who will provide a wide range of
services that will help patients in a home setting. Services include:

-- At-home injection training and follow-up visit(s)

-- Assistance in managing injection anxiety

-- Management of disease expectations

-- Tips for managing common side effects

-- Valuable phone counseling

"The AVONEX Nurse Services program is the latest example of our
efforts to provide the best care and support for patients," said
Michael Panzara, MD, MPH, Vice President and Chief Medical Officer,
Neurology Strategic Business Unit, Biogen Idec. "From our research
efforts aimed at discovering new treatment options to the unparalleled
support services we offer patients, Biogen Idec is committed to
advancing the care of people living with MS."

AVONEX has been proven to slow the progression of physical
disability, reduce the frequency of relapses, and is effective for
patients who have their first clinical MS attack and have a brain MRI
scan that suggests MS. AVONEX is also the only once-a-week therapy for
MS.

The clinical benefits of AVONEX have been supported by a number of
recent enhancements to the product's delivery. AVONEX can now be
administered with a smaller needle, which can further advance patient
comfort. The storage and transportation of AVONEX has been made even
easier with the introduction of ambient storage for the AVONEX
luer-lock prefilled syringe. A new AVOGRIP(TM) is available to aid
patients in the administration of injections. These improvements are
part of the company's efforts to improve patients' experience with
AVONEX. In addition, AVONEX patients have shown significantly higher
adherence rates than the other approved disease-modifying therapies
(DMTs).(1)

About AVONEX

AVONEX is the most prescribed treatment for relapsing forms of MS
worldwide, with more than 130,000 patients on therapy. It was launched
in the U.S. in 1996 and later in Europe for the treatment of relapsing
forms of MS to slow the progression of disability and reduce relapses.
AVONEX is marketed internationally in more than 90 countries. AVONEX
was the first treatment approved for patients who have their first
clinical MS attack and have a brain MRI scan consistent with MS; this
use was approved in Europe in 2002 and in the U.S. in 2003. The most
common side effects associated with AVONEX multiple sclerosis
treatment are flu-like symptoms, including myalgia, fever, fatigue,
headache, chills, nausea, vomiting, pain and asthenia.

AVONEX should be used with caution in patients with depression or
other mood disorders and in patients with seizure disorders. AVONEX
should not be used by pregnant women. Patients with cardiac disease
should be closely monitored. Patients should also be monitored for
signs of hepatic injury. Routine periodic blood chemistry and
hematology tests are recommended during treatment with AVONEX. Rare
cases of anaphylaxis have been reported. Please see complete
prescribing information available at www.AVONEX.com.

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/Forward-Looking Statements

This press release contains forward-looking statements that 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 the possibility that
our competitors may offer clinical benefits and treatment options that
gain greater acceptance than AVONEX, we may experience difficulty in
hiring and retaining qualified nurses or otherwise launching the
AVONEX Nurse Services program and the other risks and uncertainties
that are described in our most recent Form 10-K or 10-Q filing with
the SEC, including the "Risk Factors" section of such filings. 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.

(1) V. Devonshire et al. The Global Adherence Project (GAP) - A
Multicentre Observational Study on Adherence to Disease-Modifying
Therapies in Patients Suffering From Relapsing-Remitting Multiple
Sclerosis. Presented at the 22nd Congress of the European Committee
for Treatment and Research in Multiple Sclerosis September 27-30, 2006
Madrid, Spain. Non-adherence was defined as missing at least one
injection or changing dose within four weeks prior to the survey.