EXHIBIT 99.1

American Science and Engineering, Inc. Reports Results for

Fourth Quarter and Fiscal Year 2011 and Declares a Quarterly Dividend

The Company Reports Record Fiscal Year Revenues, Net Income, EPS, Bookings, and Backlog

BILLERICA, Mass. — May 9, 2011 — American Science and Engineering, Inc. (NASDAQ: ASEI) (“AS&E”), a leading worldwide supplier of innovative X-ray inspection solutions, today reported its financial results for the fourth quarter and fiscal year ended March 31, 2011. The Company reported revenues of $67,708,000 as compared with revenues of $71,264,000 for the fourth quarter of fiscal year 2010, net income of $9,565,000 as compared with net income of $12,326,000 for the fourth quarter of fiscal year 2010, and earnings per share of $1.03 as compared with earnings per share of $1.34 for the fourth quarter of fiscal year 2010. These results represent a 5% decrease in revenues, 22% decrease in net income, and a $0.31 decrease in earnings per share when compared to results for the fourth quarter of the prior fiscal year.

For the fiscal year ended March 31, 2011, the Company reported record revenues of $278,576,000 which represents an increase of 15% as compared with revenues of $242,093,000 for the prior fiscal year, record net income of $42,817,000 which represents an 18% increase in net income as compared with net income of $36,176,000 for the prior fiscal year, and record earnings per share of $4.63 which represents a $0.66 increase in earnings per share as compared with earnings per share of $3.97 for the prior fiscal year.

The Company reported $41,635,000 in bookings for the fourth quarter of fiscal year 2011 as compared with $43,123,000 in bookings for the fourth quarter of the prior fiscal year and a record $298,075,000 in bookings for the fiscal year ended March 31, 2011 as compared with $282,472,000 in bookings for the prior fiscal year. Backlog at March 31, 2011 increased 10% to a new record year-end backlog of $215,228,000 as compared to $195,729,000 at March 31, 2010.

The Company is declaring a quarterly cash dividend of $0.30 per share, payable on June 2, 2011 to the holders of record at the close of business on May 23, 2011.

“Once again ‘Team AS&E’ achieved outstanding year-end results with record revenues, net income, and EPS — and, we delivered strong cash flow for the fiscal year,” said Anthony Fabiano, AS&E’s President and CEO. “Revenue growth in the year was driven by market gains and the aggressive sale of existing and new products, resulting in a diversified product mix and revenue increases in all business areas.  We increased internal research and development investment 14% over last year, allowing us to introduce more new products, enhance existing products with new features and options, and accelerate the development cycle for bringing new technologies to market.”

Fabiano continued, “With our continued investment in global marketing and sales activities, our fiscal year bookings reached a record high of $298 million and increased the demand for our unique technology from our key market verticals — military, critical infrastructure, ports, and borders.  Despite the global economic uncertainties, our sales pipeline reached an all-time high at the end of the fiscal year with new opportunities in the U.S., Middle East, APAC, Latin America, and Europe.  These achievements in the year were the result of the successful execution of our strategies to grow revenue and earnings to increase shareholder value over the long-term. We’re also pleased to be able to continue to return cash to shareholders through a cash dividend.”

As previously announced, Anthony Fabiano, President and CEO, and Ken Galaznik, Senior Vice President, CFO and Treasurer, will host the quarterly conference call today at 4:30 p.m. ET to discuss the results and respond to questions. Please dial 1-800-261-3417 at least 10 minutes prior to starting time. For international participants, dial 1-617-614-3673. Please tell the Operator the confirmation code: 93037663. You will be placed on hold until the conference call is ready to begin.

An audio replay of the teleconference will be available, in its entirety, starting Monday, May 9, 2011 at 7:30 p.m. ET for a 48-hour period by dialing 1-888-286-8010. Internationally, please dial 1-617-801-6888. The conference identification number is 56526226. The replay will also be available at www.as-e.com in the Investor Information section following the conference.

About AS&E

American Science and Engineering, Inc. is a leading worldwide supplier of innovative X-ray inspection systems. With over 50 years of experience in developing advanced X-ray security systems, the Company’s product line utilizes a combination of technologies, including patented Z Backscatter™ technology, Radioactive Threat Detection (RTD), high energy transmission and dual energy transmission X-ray. These technologies offer superior X-ray threat detection for plastic explosives, plastic weapons, liquid explosives, dirty bombs and nuclear devices. AS&E’s complete range of products include cargo inspection systems for port and border security, baggage screening systems for facility and aviation security, and personnel and passenger screening systems. AS&E® systems protect high-threat facilities and help combat terrorism and trade fraud, drug smuggling, weapon smuggling, and illegal immigration and people smuggling. AS&E customers include leading government agencies, border authorities, military bases, airports and corporations worldwide, including the U.S. Department of Homeland Security (DHS), U.S. Department of Defense (DoD), U.S. Customs and Border Protection (CBP), North Atlantic Treaty Organization (NATO), and Abu Dhabi Customs. For more information on AS&E products and technologies, please visit www.as-e.com.

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, delays or cancellations (in full or in part) 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; litigation seeking to restrict the use of intellectual property used by the Company; limitations under certain laws on the Company’s ability to protect its own intellectual property; potential product liability claims against the Company; 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; the potential insufficiency of Company resources, including human resources, capital, plant and equipment and management systems, to accommodate any future growth; technical problems and other delays that could impact new product development and the Company’s ability to adapt to changes in technology and customer requirements; competitive pressures; lengthy sales cycles both in United States government procurement and procurement abroad;  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. Readers are further advised to review the “Risk Factors” set forth in the Company’s Annual Report on Form 10-K, which further detail and supplement the factors described in this Safe Harbor Statement.  Among other disclosures, the Risk Factors disclose risks pertaining to that portion of the Company’s business that is dependent on United States government contracting as well as international customers.

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AMERICAN SCIENCE AND ENGINEERING, INC.

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS

(in thousands, except per share amounts)

(unaudited)

The results of operations reported herein may not be indicative of future financial conditions or results of future operations.

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AMERICAN SCIENCE AND ENGINEERING, INC.

CONDENSED CONSOLIDATED BALANCE SHEETS

(in thousands)

(unaudited)

-continued-

AMERICAN SCIENCE AND ENGINEERING, INC.

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(in thousands)

 (unaudited)

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