PRAECIS PHARMACEUTICALS INCORPORATED Presents Update on its DirectSelect(TM) Technology

PRAECIS PHARMACEUTICALS INCORPORATED (NASDAQ: PRCS)
today announced that it is presenting an update on the development of
its DirectSelect(TM) Technology at the MedChem Europe 2006 meeting in
Prague, Czech Republic. The Company's presentation will be delivered
by Barry Morgan, Ph.D., Vice President, Chemistry, today at 8:30 a.m.
(EST). Dr. Morgan will present an overview of DirectSelect(TM)
Technology which will include a discussion regarding the generation of
a set of libraries comprising over 5 billion compounds geared towards
the identification of small molecule drug candidates, as well as the
application of these libraries towards the identification of hit
families to three well-known targets in proof-of-concept studies. A
copy of the presentation will be posted on the Company's website at
http://www.praecis.com under "Investors" following the presentation.

   PRAECIS has developed a chemistry-driven technology, called
DirectSelect(TM), which it believes will facilitate the drug discovery
process. The technology is based upon the creation of multiple,
numerically large (10 to the sixth to >10 to the ninth), encoded
libraries of drug-like structures that can be rapidly screened to
identify individual structures, or families of structures, with
affinity for a macromolecular target.

   The premise behind the DirectSelect(TM) Technology is that the
odds of identifying hits with higher affinity and enhanced selectivity
for a macromolecular target can be improved by increasing the numeric
size and "chemical space" interrogated by the target. In addition,
access to multiple, structurally diverse families should improve the
likelihood of identifying a lead molecule with a favorable safety
profile in vivo. Combinatorial libraries of small molecules have
traditionally been constrained to relatively low numbers (up to tens
of thousands) of constituents due to technical limitations associated
largely with deconvolution. PRAECIS has systematically addressed these
challenges by focusing its efforts on marrying validated chemistry
methods with unique screening and deconvolution steps.

   In the presentation, Dr. Morgan will describe the screening of
PRAECIS' libraries against two kinase and one protease target. In each
case, novel hit families were identified. In certain cases, the hits
were validated through re-synthesis, without tags used during the
library screening, and tested in biochemical and cell-based assays.

   Given the successful internal validation of the ability of this
technology to identify hit molecules in the proof-of-concept studies
referenced above, PRAECIS has initiated activities to screen for new
compounds against therapeutic targets of interest. The continued
development and enhancement of DirectSelect(TM) is an important
component of PRAECIS' strategic operating plan, and PRAECIS believes
that this technology may be an important tool for the future of drug
discovery and development. The Company intends to use its
DirectSelect(TM) technology to support pharmaceutical partnerships in
drug discovery and development and continues to initiate and advance
research collaboration discussions with various major pharmaceutical
companies with respect to this technology. The Company also intends to
use this technology to expand its own proprietary development
pipeline.

   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, including
statements regarding the Company's plans for seeking partnerships
relating to, as well as the internal use of, its DirectSelect(TM)
technology. 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. These statements are subject to
numerous risks, uncertainties and assumptions that could cause actual
events and results to differ from those anticipated or projected,
including, but not limited to, the Company's ability to continue
development of and successfully partner its DirectSelect(TM)
technology, 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 various 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.