PRAECIS PHARMACEUTICALS INCORPORATED Presents Preclinical Data on PPI-2458

PRAECIS PHARMACEUTICALS INCORPORATED (NASDAQ: PRCS)
today announced that it is presenting preclinical data on its
investigational compound, PPI-2458, at the GTC bio 3rd Cancer Drugs
Research and Development Symposium being held in San Francisco,
California. The Company's presentation, entitled "Targeted Cancer
Therapies: Inhibitors of Methionine Aminopeptidase-2," will be
delivered by William Westlin, Ph.D., Vice President, Preclinical
Research today at 5:00 p.m. (PST). Dr. Westlin will present
preclinical data supporting the Company's rationale for studying its
investigational compound PPI-2458 as a targeted molecular therapy for
non-Hodgkin's lymphoma and malignant melanoma. A copy of the
presentation will be posted on the Company's website at
http://www.praecis.com, under "Investors" following the presentation.

   PPI-2458 is a novel, proprietary small molecule belonging to the
fumagillin class of compounds that specifically targets the methionine
aminopeptidase-2 (MetAP-2) enzyme. This class of compounds has been
shown to prevent both abnormal cell growth as well as the formation of
new blood vessels (known as angiogenesis); both events are known
contributors to the growth of aberrant tissues in diseases such as
cancer and rheumatoid arthritis.

   PRAECIS is conducting a Phase 1 clinical study of PPI-2458 in
cancer patients. The study is designed to assess the safety and
tolerability of orally administered PPI-2458. As a secondary endpoint,
the study will assess the pharmacodynamic activity of PPI-2458.
Additional information about the Company's clinical trial for PPI-2458
can be accessed on the Internet at www.clinicaltrials.gov. In addition
to the ongoing clinical trial in cancer patients, the Company
continues to conduct preclinical evaluations of the use of this
compound for treating inflammatory and autoimmune disorders, including
rheumatoid arthritis.

   About PRAECIS

   PRAECIS PHARMACEUTICALS INCORPORATED is a biopharmaceutical
company focused on the discovery and development of innovative
therapies that either address unmet medical needs or offer
improvements over existing therapies. PRAECIS has a novel MetAP-2
inhibitor, PPI-2458, in clinical development for cancer indications,
including non-Hodgkin's lymphoma and solid tumors, as well as an
innovative drug discovery technology, DirectSelect(TM), which enables
the generation and practical use of ultra-large libraries for the
discovery of orally active compounds for drug development. PRAECIS has
received approval to market Plenaxis(R) in both the United States and
Germany.

   This news release contains forward-looking statements regarding
the Company's continued development of PPI-2458. These statements are
based on the Company's current beliefs and expectations as to future
outcomes and are not guarantees of future events or performance. Such
statements are subject to numerous factors and uncertainties. These
include, but are not limited to, the timing and content of decisions
made by the FDA, unexpected results in ongoing and future preclinical
or clinical trials and related analyses, and the need for additional
research and testing, including those required as a result of
unanticipated determinations by the FDA, as well as the risks set
forth from time to time in the Company's filings with the Securities
and Exchange Commission, including but not limited to the risks
discussed in the Company's Quarterly Report on Form 10-Q for the
quarter ended September 30, 2005. The Company undertakes no obligation
to update any forward-looking statement made in this press release to
reflect new information, events or circumstances after the date of
this release.