PRAECIS PHARMACEUTICALS INCORPORATED Presents Preclinical Data on PPI-2458 in Rheumatoid Arthritis

PRAECIS PHARMACEUTICALS INCORPORATED (NASDAQ: PRCS)
today announced that it is presenting preclinical data on its
investigational compound, PPI-2458, at the GTC bio Angiogenesis
Research & Therapeutics Conference being held in San Diego,
California. The Company's presentation, entitled "Molecularly Targeted
Therapy for Angiogenesis and Hyperproliferative Diseases through
Inhibition of MetAP-2," will be delivered by Gerhard Hannig, Ph.D.,
Director of Cell Biology, Preclinical Research today at 11:00 a.m.,
PST. Dr. Hannig will present preclinical data supporting the Company's
rationale for studying its investigational compound PPI-2458 as a
targeted molecular therapy with potential disease-modifying activity
in rheumatoid arthritis. 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 novel compounds
with the potential to address unmet medical needs or improve 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.