Exhibit 99.1

            VaxGen Begins Phase II Trial of Anthrax Vaccine Candidate

      BRISBANE, Calif. - April 15, 2004 - VaxGen, Inc. (Nasdaq: VXGN) announced
today that it has initiated a Phase II trial of its recombinant anthrax vaccine,
rPA102. The 13-month trial is taking place at up to 12 medical centers in the
United States and is one of two studies of rPA102 that VaxGen intends to
initiate this year under a multi-year, $80.3 million U.S. government contract
from the National Institute of Allergy and Infectious Diseases (NIAID), part of
the National Institutes of Health.

      "Given the urgent unmet need for a next-generation anthrax vaccine, VaxGen
is particularly pleased to advance the clinical development of rPA102," said
Lance K. Gordon, Ph.D., VaxGen's president and chief executive officer. "The
ability to start a Phase II clinical trial of rPA102 within months of winning
our latest anthrax contract from NIAID is a testament to VaxGen's ability to
deliver results under tight deadlines and to satisfy the regulatory and
contractual requirements of the program. We look forward to continuing what has
been a very productive public-private sector collaboration."

      The Phase II study will evaluate the safety and immunogenicity of
different formulations of rPA102 among 480 healthy volunteers. Each formulation
will contain varying concentrations of recombinant Protective Antigen (rPA) and
aluminum hydroxide, an adjuvant designed to enhance the immune response. The
goal of the study is to determine the optimal combination of rPA and the
adjuvant required to induce the most robust immune response. rPA is a synthetic
protein that induces antibodies that are designed to prevent illness by
neutralizing anthrax toxins.

      VaxGen plans to conduct a second Phase II trial of rPA102 later this year
that will be designed to determine the optimal dosing schedule for the anthrax
vaccine candidate, both for prevention and treatment of exposure to inhalation
anthrax.

      Based on the work of the U.S. Army Medical Research Institute of
Infectious Diseases, rPA102 combines the potential safety benefits of a product
made through modern recombinant technology with efficacy demonstrated in animal
models. rPA102 cannot cause anthrax infection.

      VaxGen began developing rPA102 to address the need for an anthrax vaccine
that has an improved safety profile and a more practical dosing schedule
compared to the existing licensed anthrax vaccine. The approved dosing regimen
for the only currently licensed anthrax vaccine in the United States, AVA,
requires six doses administered over an 18-month period.

      VaxGen launched a Phase I trial of rPA102 in the second quarter of 2003
that compared the safety and immunogenicity of escalating doses of rPA102 to
those of AVA. The results of the study, presented at the International
Conference on Emerging Infectious Diseases (ICEID) in Atlanta on March 2nd,
indicated that rPA102 elicited an immune response comparable to that of



AVA, even though AVA contained more than 10 times the amount of adjuvant. The
study also demonstrated a dose-response relationship in all rPA treatment
groups. rPA102 was well-tolerated, with no significant safety or reactogenicity
issues.

      About VaxGen

      VaxGen, Inc. is a biopharmaceutical company engaged in the development,
manufacture and commercialization of biologic products for the prevention and
treatment of human infectious diseases. Based in Brisbane, Calif., the company
is developing preventive vaccines against anthrax, smallpox and plague and an
anthrax monoclonal antibody in collaboration with AVANIR Pharmaceuticals. The
company is also the largest shareholder in Celltrion, Inc., a joint venture
formed to build operations for the manufacture of biopharmaceutical products,
including VaxGen's product candidates. For more information, please visit the
company's web site at: www.vaxgen.com.

NOTE: This press release contains "forward-looking statements" within the
meaning of the federal securities laws. These forward-looking statements include
without limitation, statements regarding the timing, progress and results of
VaxGen's clinical development of rPA102, the ultimate safety and efficacy of
rPA102 and VaxGen's ability or intentions to sell the vaccine. These statements
are subject to risks and uncertainties that could cause actual results and
events to differ materially from those anticipated. Reference should be made to
Item 1 of the company's Annual Report on Form 10-K filed by VaxGen on March 30,
2004 under the heading "Additional Business Risks" for a more detailed
description of such factors. Readers are cautioned not to place undue reliance
on these forward-looking statements that speak only as of the date of this
release. VaxGen undertakes no obligation to update publicly any forward-looking
statements to reflect new information, events or circumstances after the date of
this release except as required by law.

Media Contact

Kesinee Angkustsiri Yip, Associate Director
Corporate Communications
650-624-2304

Investor Contact

Lance Ignon
Vice President, Corporate Affairs
650-624-1041