Alnylam Appoints James L. Vincent as Director; Appointment Strengthens Board with Former CEO of Top-Tier Biopharmaceutical Company.

CAMBRIDGE, Mass. -- Alnylam Pharmaceuticals, Inc. (Nasdaq: ALNY), a leading RNAi therapeutics company, announced today the appointment of James L. Vincent as a Director.

Mr. Vincent was formerly Chief Executive Officer and Chairman of Biogen, Inc. (now BiogenIdec, Inc.) between 1985-2002. At Biogen, Mr. Vincent built one of the world's leading fully-integrated biopharmaceutical companies and led the successful transition of Biogen from a research company to an operating company. Prior to Biogen, Mr. Vincent served in numerous managerial leadership roles at Allied-Signal, Inc., Abbott Laboratories, Inc., and Texas Instruments, Inc. He currently serves on the Board of Trustees for Duke University.

"The appointment of Jim to the Alnylam Board will greatly enhance Alnylam's efforts to build a leading product company founded on the discoveries of RNAi," said John Maraganore, Ph.D., President and Chief Executive Officer of Alnylam Pharmaceuticals. "Jim is aptly credited with the development and execution of a masterful strategy that led to the creation of one of the world's leading biopharmaceutical companies, and we are very fortunate to have this experience as part of our organization."

"I am delighted to join the Alnylam Board and work with management in the strategic development of the company," said James L. Vincent. "I believe the discovery of RNAi and its translation to products create a unique opportunity, which is rare in modern biology, to build an entirely new class of therapeutics."

About RNA Interference (RNAi)

RNA interference, or RNAi, is a naturally occurring mechanism within cells for selectively silencing and regulating specific genes. Since many diseases are caused by the inappropriate activity of specific genes, the ability to silence and regulate such genes selectively through RNAi could provide a means to treat a wide range of human diseases. The discovery of RNAi has been heralded by many as a major breakthrough, and the journal Science named RNAi the top scientific achievement of 2002, as well as one of the top 10 scientific advances of 2003.

About Alnylam

Alnylam is a biopharmaceutical company seeking to develop and commercialize novel therapeutics based on RNA interference, or RNAi. Growing from its foundation as the world's first company focused on RNAi therapeutics, the company's leadership in the field of RNAi is supported by its preeminent founders and advisors and its strengths in fundamental patents, technology, and know-how that underlie the commercialization of RNAi therapeutics. Alnylam is developing a pipeline of RNAi products using Direct RNAi(TM) to treat ocular, central nervous system, and respiratory diseases and Systemic RNAi(TM) to treat a broad range of diseases, including oncology, metabolic, and autoimmune diseases. The company's global headquarters are in Cambridge, Massachusetts. For additional information, please visit www.alnylam.com.

Alnylam Forward-Looking Statements

Various statements in this release concerning our future expectations, plans, prospects and future operating results constitute forward-looking statements for the purposes of the safe harbor provisions under The Private Securities Litigation Reform Act of 1995. Actual results may differ materially from those indicated by these forward-looking statements as a result of various important factors, including risks related to: our approach to discover and develop novel drugs, which is unproven and may never lead to marketable products; our ability to obtain additional funding to support our business activities; our dependence on third parties for development, manufacture, marketing, sales and distribution of our products; the successful development of products, all of which are in early stages of development; obtaining regulatory approval for products; competition from others using technology similar to ours and others developing products for similar uses; obtaining, maintaining and protecting intellectual property utilized by our products; and our short operating history; as well as those risks more fully discussed in the "Certain Factors That May Affect Future Results" section of our most recent Form 10-Q filed with the Securities and Exchange Commission. In addition, any forward-looking statements represent our views only as of today and should not be relied upon as representing our views as of any subsequent date. We do not assume any obligation to update any forward-looking statements.