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                                                      Contact: Kristina Peterson
                                                      (760) 603-2521



       ISIS PHARMACEUTICALS' IBIS THERAPEUTICS DIVISION AWARDED ADDITIONAL
          2-YEAR, $7.1 MILLION CONTRACT TO DEVELOP DETECTION DEVICE FOR
                           BIOLOGICAL WARFARE DEFENSE

 LATEST AWARD BUILDS ON $1.8 MILLION DARPA CONTRACT ANNOUNCED EARLIER THIS MONTH

CARLSBAD, CA, OCTOBER 25 - Isis Pharmaceuticals, Inc. (NASDAQ: ISIP) announced
today that its Ibis Therapeutics(TM) division has received an additional
two-year contract with the Defense Advanced Research Projects Agency (DARPA) to
develop a sensor to detect infectious agents used in biological warfare attacks.
This two-year contract is currently valued at up to an additional $7.1 million
for the research program Triangulation Identification Genetic Evaluation of
biological Risks (TIGER). Earlier this month, Isis announced the receipt of a
$1.8 million award for the TIGER program, bringing the total of the TIGER
contract to up to $8.9 million. Over the past year, San Diego-based Science
Applications International Corporation (SAIC) and Ibis Therapeutics have worked
together to receive the TIGER program award. The SAIC and Ibis Therapeutics
partnership will combine Ibis' expertise in microbial genome sequence analysis
and advanced mass spectrometry technology with SAIC's advanced signal processing
capabilities.

"We are pleased to be collaborating with an outstanding team of experts from
SAIC on this important project. The combination of Ibis and SAIC's expertise
creates a unique team that has the abilities to tackle this difficult problem
with innovative technological solutions," said David J. Ecker, Ph.D., President
of Ibis Therapeutics. "As a research team and as a company, we are proud to be
selected by DARPA to contribute our technology and expertise to assist in
protecting our citizens against a biological attack."

The TIGER contract builds on the biological warfare countermeasure research Ibis
Therapeutics has conducted in two previous DARPA programs. The preceding
studies, initiated in 1997 and 1999, focused on creating a strategy to identify
common binding sites, or structured regions within RNA, to a wide range of
infectious agents in order to develop small molecules to combat infectious
pathogens. Ibis' work for DARPA has yielded a number of proprietary targets and
significant advances in RNA-targeted drug design. With this award, Ibis has
received government-funded contracts totaling approximately $18 million.

Ibis Therapeutics has developed a novel program focused on the discovery of low
molecular weight, orally bioavailable drugs that work by binding to RNA targets
implicated in disease processes. The program is enabled by a technology platform
that integrates functional genomics, informatics and an RNA-focused chemistry
program coupled with novel, high throughput mass spectrometry-based screening
methods. Ibis Therapeutics has initially focused on antibacterials, antivirals
and antifungals as areas of therapeutic emphasis.

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Isis will conduct a live webcast conference call to discuss this release on
Friday, October 26th at 9:30 AM Eastern time. To participate over the internet,
go to www.isip.com. A replay of the webcast will be available at this address
for up to two weeks.

Isis Pharmaceuticals, Inc. is exploiting its expertise in RNA to discover and
develop novel human therapeutic drugs. Isis has 12 antisense products in its
development pipeline with two in late-stage development and six in Phase II
human clinical trials. Isis' GeneTrove(TM) division uses antisense to assist
pharmaceutical industry partners in validating and prioritizing potential gene
targets through customized services and access to an extensive gene function
database. Ibis Therapeutics is a division focused on the discovery of small
molecule drugs that bind to RNA. Isis has a broad patent estate as the owner or
exclusive licensee of more than 800 issued patents worldwide.

This press release contains forward-looking statements pertaining to Ibis
Therapeutics, a division of Isis Pharmaceuticals, Inc. Such statements are
subject to certain risks and uncertainties, particularly those inherent in the
process of working under government contract and in developing technology and
devices used in the detection of infectious agents used in biological attacks
and in the process of discovering, developing and commercializing drugs and
sensors that are safe and effective for use as human therapeutics and devices
and financing such activities. Actual results could differ materially from those
projected in this release. As a result, you are cautioned not to rely on these
forward-looking statements. These and other risks concerning Isis' research and
development programs are described in additional detail in the Registration
Statement on Form S-3 as amended on October 22, 2001 with the U.S. Securities
and Exchange Commission, copies of which are available from the company.

GeneTrove(TM) and Ibis Therapeutics(TM) are trademarks of Isis Pharmaceuticals,
Inc.




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