EXHIBIT 99.1

                              FOR IMMEDIATE RELEASE

    AMERICAN SCIENCE AND ENGINEERING, INC. RECEIVES SERVICE AND MAINTENANCE
                      CONTRACT VALUED UP TO $13.2 MILLION

BILLERICA, MASS. - SEPTEMBER 21, 2004 - AMERICAN SCIENCE AND ENGINEERING, INC.
(AMEX: ASE) (AS&E(R)), A LEADER IN X-RAY DETECTION TECHNOLOGY, ANNOUNCED TODAY
THE RECEIPT OF A ONE-YEAR CONTRACT VALUED UP TO $13.2 MILLION TO PROVIDE
MAINTENANCE AND SUPPORT OF ITS MOBILESEARCH(TM) X-RAY INSPECTION SYSTEMS FOR A
U.S. GOVERNMENT AGENCY. THE ORDER REPRESENTS A FIXED-PRICE VALUE OF $8.6
MILLION, AND ENGAGES AS&E to provide regularly scheduled maintenance services on
the MobileSearch systems. The remaining $4.6 million of this order, for services
and/or spare parts, is an estimation of the customer's historical usage
requirements, which will be recognized on the basis of actual utilization.

"This contract is a significant business development milestone for AS&E," said
Anthony Fabiano, President and CEO. "Our people have worked tirelessly over the
past several months to provide higher levels of service and response to our
valued customers. We intend to provide the United States Government with the
highest quality of technical support for its MobileSearch systems. This order
reflects their growing confidence in our capabilities. With a reputation for
outstanding customer satisfaction, our Service and Support group continues to be
a key contributor to top and bottom-line growth -- this order further
underscores this trend."

The MobileSearch X-ray inspection system provides U.S. security officials with a
highly effective means for detecting weapons, plastic explosives, illegal drugs,
and other contraband, utilizing traditional transmission X-rays in combination
with proprietary Z(R) Backscatter technology.

AS&E's highly skilled Field Service Engineers (FSEs) provide support services
worldwide. FSEs are available 7 days a week, 24 hours a day, and are located at
AS&E offices in Asia, Europe, the Middle East and North America. In addition,
AS&E has assembled a world-class Technical Support and Call Coordinator staff at
headquarters in Billerica. They ensure that customers' X-ray inspection systems
are serviced in the most timely and effective manner possible.

ABOUT AS&E(R)

AMERICAN SCIENCE AND ENGINEERING, INC. DEVELOPS AND MANUFACTURES
STATE-OF-THE-ART X-RAY INSPECTION SYSTEMS FOR HOMELAND SECURITY AND OTHER
CRITICAL DEFENSE APPLICATIONS. AS&E CONTINUES TO INNOVATE, CREATE AND DEVELOP
NEW PRODUCTS BY INVESTING IN NEW IDEAS THROUGH RESEARCH AND DEVELOPMENT, AND
EVOLVING ITS TECHNOLOGY TO MEET THE NEEDS OF AN EVER-CHANGING WORLD. AS&E'S
PATENTED Z(R) BACKSCATTER TECHNOLOGY DETECTS PLASTIC EXPLOSIVES, ILLEGAL DRUGS,
AND OTHER CONTRABAND, EVEN WHEN ARTFULLY CONCEALED IN COMPLEX BACKGROUNDS BY
TERRORISTS AND SMUGGLERS. AS&E's SHAPED ENERGYTM X-RAY INSPECTION SYSTEMS
COMBINE THE MATERIAL DISCRIMINATION FEATURES OF Z(R) BACKSCATTER IMAGING WITH
THE PENETRATION CAPABILITY OF HIGH-ENERGY X-RAYS FOR DENSE CARGOES, WITHOUT THE
PROBLEMS CAUSED BY EXCESSIVE RADIATION. AS&E'S HIGH ENERGY SYSTEMS DIVISION
MANUFACTURES LINEAR ACCELERATORS FOR A VARIETY OF APPLICATIONS INCLUDING
MEDICAL, SCIENTIFIC, SECURITY, ELECTRON BEAM CURING AND NON-DESTRUCTIVE TESTING.
FOR MORE INFORMATION ON AS&E PRODUCTS AND TECHNOLOGIES, PLEASE VISIT
HTTP://WWW.AS-E.COM.

For more information:
---------------------
Laura Berman
American Science and Engineering, Inc.
(978) 262-8700

SAFE HARBOR STATEMENT. THE FOREGOING PRESS RELEASE CONTAINS STATEMENTS
CONCERNING AS&E'S FINANCIAL PERFORMANCE, MARKETS AND BUSINESS OPERATIONS THAT
MAY BE CONSIDERED "FORWARD-LOOKING" UNDER APPLICABLE SECURITIES LAWS. AS&E
WISHES TO CAUTION READERS OF THIS PRESS RELEASE THAT ACTUAL RESULTS MIGHT DIFFER
MATERIALLY FROM THOSE PROJECTED IN ANY FORWARD-LOOKING STATEMENTS. FACTORS WHICH
MIGHT CAUSE ACTUAL RESULTS TO DIFFER MATERIALLY FROM THOSE PROJECTED IN THE
FORWARD-LOOKING STATEMENTS CONTAINED HEREIN INCLUDE THE FOLLOWING: SIGNIFICANT
REDUCTIONS OR DELAYS IN PROCUREMENTS OF THE COMPANY'S SYSTEMS BY THE UNITED
STATES AND OTHER GOVERNMENTS; DISRUPTION IN THE SUPPLY OF ANY SOURCE COMPONENT
INCORPORATED INTO AS&E's products and other factors which may cause delays in
production and delivery schedules; LITIGATION SEEKING TO RESTRICT THE USE OF
INTELLECTUAL PROPERTY USED BY THE COMPANY; POTENTIAL PRODUCT LIABILITY CLAIMS
AGAINST THE COMPANY; FAILURE OF ANY OF OUR PRODUCTS TO MEET PERFORMANCE
REQUIREMENTS OR TO CONTINUE TO OPERATE RELIABLY BECAUSE OF UNEXPECTED DESIGN
FLAWS OR MANUFACTURING DEFECTS, GLOBAL POLITICAL TRENDS AND EVENTS WHICH AFFECT
PUBLIC PERCEPTION OF THE THREAT PRESENTED BY DRUGS, EXPLOSIVES AND OTHER
CONTRABAND; GLOBAL ECONOMIC DEVELOPMENTS AND THE ABILITY OF GOVERNMENTS AND
PRIVATE ORGANIZATIONS TO FUND PURCHASES OF THE COMPANY'S PRODUCTS TO ADDRESS
SUCH THREATS; AND THE POTENTIAL INSUFFICIENCY OF COMPANY RESOURCES, INCLUDING
HUMAN RESOURCES, CAPITAL, PLANT AND EQUIPMENT AND MANAGEMENT SYSTEMS, TO
ACCOMMODATE ANY FUTURE GROWTH, AND FUTURE DELAYS IN FEDERAL FUNDING. THESE AND
CERTAIN OTHER FACTORS WHICH MIGHT CAUSE ACTUAL RESULTS TO DIFFER MATERIALLY FROM
THOSE PROJECTED ARE DETAILED FROM TIME TO TIME IN AS&E'S PERIODIC REPORTS AND
REGISTRATION STATEMENTS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION, WHICH
IMPORTANT FACTORS ARE INCORPORATED HEREIN BY REFERENCE. AS&E UNDERTAKES NO
OBLIGATION TO UPDATE FORWARD LOOKING STATEMENTS TO REFLECT CHANGED ASSUMPTIONS,
THE OCCURRENCE OF UNANTICIPATED EVENTS, OR CHANGES IN FUTURE OPERATING RESULTS,
FINANCIAL CONDITION OR BUSINESS OVER TIME.