CAMBRIDGE, MA — July 25, 2005
Momenta Pharmaceuticals, Inc. (Nasdaq: MNTA), a biotechnology company developing drugs based on its proprietary sugar sequencing technology, will report its financial results for the second quarter ended June 30, 2005 before the U.S. financial markets open on Wednesday, August 10, 2005.

Management will host a conference call on that date at 10:00 am EDT to discuss these results and provide an update on the company. To access the call, please dial 866-700-7173 (domestic) or 617-213-8838 (international) prior to the scheduled conference call time and provide the access code 19905356. A replay of the call will be available approximately two hours after the call and will be accessible through August 17, 2005. To access the replay, please dial 888-286-8010 (domestic) or 617-801-6888 (international) and provide the access code 44855780.

A live audio webcast of the call will be available on the “Investors” section of the Company’s website, www.momentapharma.com. Please go to the site at least 15 minutes prior to the call in order to register, download, and install any necessary software. An archived version of the webcast will be posted on the Momenta website approximately two hours after the call and will be available through September 10, 2005.

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 biologic 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 the website at www.momentapharma.com, which does not form a part of this press release.

Forward Looking Statements:
Statements in this press release regarding Momenta Pharmaceuticals Inc.’s future expectations, beliefs, goals, plans or prospects constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Momenta’s actual results could differ materially from those stated or implied in forward-looking statements due to a number of factors, including those factors contained in Momenta’s Annual Report on Form 10-K for the year ended December 31, 2004 filed with the Securities and Exchange Commission under the section “Risk Factors That May Affect Results,” as well as other documents that may be filed by Momenta from time to time with the Securities and Exchange Commission. Forward-looking statements include statements regarding Momenta’s expectations, beliefs, intentions or strategies regarding the future and can be identified by forward-looking words such as “anticipate”, “believe”, “could”, “estimate”, “expect”, “intend”, “may”, “should”, “will”, and “would” or similar words. Momenta assumes no obligations to update the information included in 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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