Exhibit 99.1

                                                                    News Release

FOR IMMEDIATE RELEASE
May 15, 2003

Contact: Alan R. Engbring                             Martha J. Demski
         Director, Investor Relations                 Vice President and
         (858) 646-1127                               Chief Financial Officer

        VICAL ANNOUNCES REVISION OF FIRST QUARTER 2003 FINANCIAL RESULTS

SAN DIEGO--May 15, 2003--Vical  Incorporated  (Nasdaq:VICL) today announced that
the company has revised its revenue,  expense and net loss numbers for the first
quarter ended March 31, 2003, from those previously reported on May 5, 2003. The
revised  financials  can be found in greater  detail in the company's  Form 10-Q
filed today with the  Securities  and  Exchange  Commission,  which is available
through the company's web site at  www.vical.com.  The revised  revenues for the
quarter are $0.9 million,  compared with the  previously  reported $1.6 million.
The revised operating  expenses for the quarter are $8.6 million,  compared with
the  previously  reported $8.9 million.  The  difference in revenues and related
expenses  reflects the portion of a contract  manufacturing  order which was not
shipped  during the quarter,  but for which full payment had been  received from
the  customer.  The net result of these  changes in revenues  and  expenses is a
revised  net  loss of $7.0  million,  or  $0.35  per  share,  compared  with the
previously reported $6.6 million, or $0.33 per share.

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