Exhibit 99.1

 Avant Immunotherapeutics Reports Second Quarter Fiscal 2004 Financial Results

     NEEDHAM, Mass.--(BUSINESS WIRE)--July 22, 2004--AVANT Immunotherapeutics,
Inc. (Nasdaq: AVAN) today reported financial results for the second quarter
ended June 30, 2004. The company reported a net loss of $3.9 million, or $.05
per share, for the second quarter of 2004 compared to a net loss of $3.2
million, or $.05 per share, for the second quarter of 2003. For the six months
ended June 30, 2004, the company reported a net loss of $5.8 million, or $.08
per share, compared to a net loss of $6.5 million, or $.11 per share, for the
six months ended June 30, 2003.
     The increased loss for the second quarter of 2004 of $715,500, or 22.5%,
primarily reflects an increase in operating expense compared to the same period
in 2003. The increase in operating expense is primarily due to increased
clinical trial costs associated with the ongoing TP10 Phase IIb study in women
undergoing cardiac bypass surgery and TP10 contract manufacturing costs incurred
for process development and scale-up work in preparation for the production of
Phase III clinical materials in 2005. The increase in investment income
reflected higher average cash balances in 2004. At June 30, 2004, AVANT reported
cash and cash equivalents of $39.4 million.
     The six-month results for 2004 reflect a decrease in net loss of $737,300,
or 11.3%, compared to the same period in 2003. This decrease in net loss
primarily reflects an increase in revenue and an increase in investment income,
offset in part by an increase in operating expense. The increase in revenue in
2004 results primarily from the recognition of $1 million in revenue from
DynPort Vaccine Company LLC ("DVC") for rPA clinical materials and the
recognition of an upfront license fee of $1 million from AdProTech, Ltd. The
increase in operating expense results primarily from an increase in clinical
trials costs and contract manufacturing costs incurred on the company's TP10
complement inhibitor program. The increase in investment income reflects higher
average cash balances between periods.
     Una S. Ryan, Ph.D., AVANT's President and Chief Executive Officer, said,
"These financial results were consistent with our expectations. We expect,
however, that operating expenses will increase further in the third and fourth
quarters of 2004 as we begin to prepare our TP10 program in cardiac surgery for
an anticipated Phase III trial by the end of 2005. Net loss for 2004 is now
forecasted to be in the range of $17-$19 million."
     Shortly after the close of the quarter, we were pleased to announce that
the Mexican Board of Health approved the marketing of Rotarix(R) in Mexico. In
addition, we had several noteworthy accomplishments during the second quarter
which further prepare us to become a commercial company including:

     --   The award of an additional subcontract by DVC for $3 million to
          support the human clinical testing of a plague vaccine candidate being
          developed by AVANT for use in our oral combination vaccine against
          anthrax and plague.

     --   Presentation of data at a recent scientific meeting showing that four
          of AVANT's vaccines manufactured and dried using the VitriLife(R)
          preservation technology remain stable and immunogenic even when stored
          at or above normal room temperatures.

     --   Initiation by The Walter Reed Army Institute of Research (WRAIR) of a
          placebo-controlled, Phase I clinical trial to assess the safety and
          immunogenicity of an HIV vaccine based on AVANT's Therapore(R)
          technology.

     --   Expansion of our senior management team with the appointment of
          Timothy Cooke, Ph.D., as Senior Vice President, Commercial
          Development.

     --   Receipt of a building permit for our pilot manufacturing facility in
          Fall River and the start of construction. This facility will implement
          our VitriLife(R) technology.

     Rotarix(R) Vaccine

     Last week we announced that our partner, GlaxoSmithKline Biologicals (GSK),
had received approval from the Mexican Board of Health to market Rotarix(R) in
Mexico for the prevention of gastroenteritis caused by rotavirus infection.
     "We are delighted to announce this initial approval for Rotarix(R), which
marks a significant milestone for AVANT - the first commercial approval of a
human healthcare product from AVANT's extensive portfolio of advanced vaccines,"
said Una S. Ryan, AVANT President and Chief Executive Officer. "We anticipate
that this is just the first of a series of marketing approvals for Rotarix(R) as
GSK continues its worldwide development efforts for this vaccine."
     More than 70,000 infants have been enrolled in the global clinical
development program, with studies conducted in Europe, the US, Latin America and
Asia to evaluate the safety and efficacy of Rotarix(R). These studies
demonstrate that Rotarix(R) is an effective, safe and well-tolerated vaccine.

     TP10 for Cardiac Surgery

     We anticipate completing enrollment in the Phase IIb study in women
undergoing cardiac bypass surgery by the end of this year. We are working
closely with our partner, Lonza Biologics plc, to complete process development
and scale-up efforts this year in preparation for the production of Phase III
clinical materials and the start of that trial by year-end 2005.

     CETP Vaccine for Cholesterol Management

     We continue to evaluate a number of new adjuvants and delivery technologies
for our CETP vaccine in animal models and expect to choose the approach
eliciting the most robust antibody response by year-end. We are strongly
committed to this program and expect to have a CETP vaccine back into the clinic
towards the end of 2005.

     Webcast and Conference Call

     Dr. Ryan and Mr. Catlin will host a conference call at 11:00 AM EDT on
Thursday, July 22, 2004 to discuss AVANT's Second Quarter 2004 financial
results. To access the conference call, dial 800-599-9829 (within the United
States), or 617-847-8703 (if calling from outside the U.S.). The passcode for
participants is 35032838. An audio replay will be available approximately two
hours after the call for approximately one week and can be accessed by dialing
888-286-8010 (within the U.S.), or 617-801-6888 (if calling from outside the
U.S.). The passcode I.D.# is 21484786.
     A live webcast of the conference call, together with this press release,
can be accessed through the company's web site www.avantimmune.com in the
Investor Information section. In order to access the webcast, your PC must have
a sound card, speakers and Windows Media Player software. It is recommended that
you configure your PC in advance of the webcast as the software download and
installation can take several minutes. In addition, the call and webcast will be
archived and can be accessed through the same link. Additionally, a copy of this
press release is available by contacting Investor Relations at (781) 433-0771.
     AVANT Immunotherapeutics, Inc. discovers, develops and sells innovative
vaccines and therapeutics that harness the human immune system to prevent and
treat disease. The company has developed a broad, well-staged pipeline of
vaccines and therapeutics for large, high-value, under-served markets. These
include an oral human rotavirus vaccine, which gained its first marketing
approval in Mexico in July 2004. Six of AVANT's products are in clinical
development, including a treatment to reduce complement-mediated tissue damage
associated with cardiac by-pass surgery, and a novel vaccine for cholesterol
management. AVANT has also assembled a technology platform that enables the
creation of rapid-protecting, single-dose, oral vaccines that remain stable
without refrigeration. The company is developing applications of this vaccine
technology in four areas: biodefense, travelers' vaccines, global health needs,
and human food safety. AVANT's goal is to demonstrate proof-of-concept for its
products before leveraging further development through both traditional
pharmaceutical partnerships and collaborations with governmental and other
organizations.
     Additional information on AVANT Immunotherapeutics, Inc. can be obtained
through our site on the World Wide Web: http://www.avantimmune.com.

     Safe Harbor Statement Under the Private Securities Litigation Reform Act of
1995: This release includes forward-looking statements which reflect AVANT's
current views with respect to future events and financial performance. These
forward-looking statements are based on management's beliefs and assumptions and
information currently available. The words "believe", "expect", "anticipate",
"intend", "estimate", "project" and similar expressions which do not relate
solely to historical matters identify forward-looking statements. Investors
should be cautious in relying on forward-looking statements because they are
subject to a variety of risks, uncertainties, and other factors that could cause
actual results to differ materially from those expressed in any such
forward-looking statements. These factors include, but are not limited to: (1)
the integration of multiple technologies and programs; (2) the ability to adapt
AVANT's vectoring systems to develop new, safe and effective orally administered
vaccines against anthrax and plague or other bioterrorism threats or emerging
health care threats; (3) the ability to successfully complete development and
commercialization of TP10, CETi-1, CholeraGarde(R) (Peru-15), Ty800 and other
products; (4) the cost, timing, scope and results of ongoing safety and efficacy
trials of TP10, CETi-1, CholeraGarde(R) (Peru-15), Ty800 and other preclinical
and clinical testing; (5) the ability to successfully complete product research
and further development, including animal, pre-clinical and clinical studies of
TP10, CETi-1, CholeraGarde(R) (Peru-15), Ty800 and other products; (6) the
ability of the Company to manage multiple late stage clinical trials for a
variety of product candidates; (7) royalty revenues from product sales of
Rotarix(R), Megan(R)Vac 1, Megan(R)Egg and other future products; (8) changes in
existing and potential relationships with corporate collaborators; (9) the
availability, cost, delivery and quality of clinical and commercial grade
materials supplied by contract manufacturers; (10) the timing, cost and
uncertainty of obtaining regulatory approvals to use TP10, CETi-1,
CholeraGarde(R) (Peru-15) and Ty800, among other purposes, for adults undergoing
cardiac surgery, to raise serum HDL cholesterol levels and to protect travelers
and people in endemic regions from diarrhea causing diseases, respectively; (11)
the ability to obtain substantial additional funding; (12) the ability to
develop and commercialize products before competitors; (13) the ability to
retain certain members of management; and (14) other factors detailed from time
to time in filings with the Securities and Exchange Commission. We expressly
disclaim any responsibility to update forward-looking statements.


                    AVANT IMMUNOTHERAPEUTICS, INC.
CONSOLIDATED
  STATEMENTS
  OF OPERATIONS             Quarter                   Year to Date
  DATA                      Ended June 30,            Ended June 30,
- ----------------------------------------------------------------------
                          2004         2003         2004         2003
                           (Unaudited)               (Unaudited)
 REVENUE
 Product
  Development and
  Licensing
  Agreements          $124,400     $187,000   $2,248,800     $333,800
 Government
  Contracts and
  Grants               714,700      849,300    1,594,600    1,348,900
 Product Royalties      53,900       42,100       80,300       77,400
- ----------------------------------------------------------------------
 Total Revenue         893,000    1,078,400    3,923,700    1,760,100
- ----------------------------------------------------------------------

 OPERATING EXPENSE
 Research and
  Development        3,367,800    2,673,400    6,821,000    5,365,900
 General and
  Administrative     1,269,700    1,351,700    2,561,800    2,576,400
 Amortization of
  Acquired
  Intangible Assets    248,800      248,800      497,600      497,600
- ----------------------------------------------------------------------
 Total Operating
  Expense            4,886,300    4,273,900    9,880,400    8,439,900
- ----------------------------------------------------------------------

 Operating Loss     (3,993,300)  (3,195,500)  (5,956,700)  (6,679,800)

 Investment
  Income, Net           94,500       12,200      148,500      134,300
- ----------------------------------------------------------------------

 Net  Loss         $(3,898,800) $(3,183,300) $(5,808,200) $(6,545,500)
- ----------------------------------------------------------------------

 Basic and Diluted
  Net Loss per
  Common Share          $(0.05)      $(0.05)      $(0.08)      $(0.11)
- ----------------------------------------------------------------------
 Weighted Average
  Common Shares
  Outstanding       74,091,600   60,468,700   71,655,100   60,468,700
- ----------------------------------------------------------------------



 CONDENSED CONSOLIDATED
 BALANCE SHEETS                               March 31,   December 31,
- ----------------------------------------------------------------------
                                                  2004           2003
                                             (Unaudited)
 ASSETS
 Cash and Cash Equivalents                   $39,370,700  $20,251,000
 Other Current Assets                            830,400    2,058,000
 Property and Equipment, net                   1,113,200      912,700
 Intangible and Other Assets, net              7,585,800    8,083,400
                                             ------------ ------------
      Total Assets                           $48,900,100  $31,305,100
                                             ============ ============

 LIABILITIES AND STOCKHOLDERS' EQUITY
 Current Liabilities                          $3,329,300   $3,385,400
 Stockholders' Equity                         45,570,800   27,919,700
                                             ------------ ------------
 Total Liabilities and Stockholders' Equity  $48,900,100  $31,305,100
                                             ============ ============


    CONTACT: AVANT Immunotherapeutics
             Una S. Ryan, 781-433-0771
             Avery W. Catlin, 781-433-0771
             info@avantimmune.com
                 or
             For Media:
             Kureczka/Martin Associates
             Joan Kureczka, 415-821-2413
             jkureczka@aol.com