CAMBRIDGE, MA — April 7, 2006 – Momenta Pharmaceuticals, Inc. (Nasdaq: MNTA), a biotechnology company developing drugs based on its proprietary sugar sequencing technology, announced today that Paul D. Goldenheim, M.D. has been elected to Momenta’s Board of Directors, effective May 29, 2006.

Most recently, Dr. Goldenheim was President of TransForm Pharmaceuticals, Inc., a company that develops new and improved medicines through form and formulation optimization. Under his leadership, TransForm advanced the clinical development of its first two proprietary products and was acquired by Johnson and Johnson, Inc. Prior to joining TransForm in 2004, Dr. Goldenheim was Executive Vice President and Chief Scientific Officer of Purdue Pharma L.P., where he served for almost twenty years. He received his A.B. from Harvard College magna cum laude with highest honors in biochemical sciences and his M.D. from Harvard Medical School.

“Paul brings many talents to our Board of Directors. Most importantly, Paul’s extensive background in pre-clinical and clinical development will provide us valuable insight as we pursue our development and commercial programs,” said Alan Crane, Chief Executive Officer of Momenta. “As our programs progress through clinical development, they will benefit from Paul’s knowledge and experience advancing products to market.”

Dr. Goldenheim will replace Christoph Westphal, M.D., Ph.D., Chief Executive of Sirtris Pharmaceuticals, Inc., who has resigned from the Board, effective May 29, 2006. “I want to thank Christoph for his many contributions to Momenta,” continued Mr. Crane. “In his position at Polaris Venture Partners, he was our initial CEO and integral to the founding, initial financing and early development of Momenta when it was a small, development stage company. I wish him continued success in his endeavors.”

About Momenta
Momenta Pharmaceuticals, Inc. is a biotechnology company specializing in the detailed structural analysis and design of complex sugars for the development of improved versions of existing drugs, the development of novel drugs and the discovery of new biological processes. Momenta is also utilizing its ability to sequence sugars to create technology-enabled generic versions of sugar-based and complex drug products. The Company’s most advanced product candidate is M-Enoxaparin, a technology-enabled generic version of Lovenox®. Based on its understanding of complex sugars, Momenta has created a diversified pipeline of near-term product opportunities, novel development products and discovery candidates. Momenta was founded in 2001 and is headquartered in Cambridge, MA.

To receive additional information about Momenta, please visit our website at www.momentapharma.com, which does not form a part of this press release.

Our logo, trademarks, and service marks are the property of Momenta Pharmaceuticals, Inc. All other trade names, trademarks, or service marks are property of their respective owners.

Contact:
Michael A. Lawless
Momenta Pharmaceuticals, Inc.
617-395-5189

Press Contact
press@momentapharma.com

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