**Exhibit 31.1**

 

**CERTIFICATION OF CHIEF EXECUTIVEOFFICER**

**Section 302 Certification**

 

I, Anthony R. Fabiano,certify that:

 

1.               I have reviewed thisquarterly report on Form 10-Q of American Science andEngineering, Inc.;

 

2.               Based on my knowledge, thisreport does not contain any untrue statement of a material fact or omit tostate a material fact necessary to make the statements made, in light of thecircumstances under which such statements were made, not misleading withrespect to the period covered by this report;

 

3.               Based on my knowledge, thefinancial statements, and other financial information included in this report,fairly present in all material respects the financial condition, results ofoperations and cash flows of the registrant as of, and for, the periodspresented in this report;

 

4.               The registrant’s othercertifying officer and I are responsible for establishing and maintainingdisclosure controls and procedures (as defined in Exchange ActRules 13a-15(e) and 15d-15(e)) and internal control over financialreporting (as defined in Exchange Act rules 13a-15(f) and 15d-15(f))for the registrant and have:

 

a.               Designed suchdisclosure controls and procedures, or caused such disclosure controls andprocedures to be designed under our supervision to ensure that materialinformation relating to the registrant, including its consolidatedsubsidiaries, is made known to us by others within those entities, particularlyduring the period in which this report is being prepared;

 

b.              Designed suchinternal control over financial reporting, or caused such internal control overfinancial reporting to be designed under our supervision, to provide reasonableassurance regarding the reliability of financial reporting and the preparationof financial statements for external purposes in accordance with generallyaccepted accounting principles;

 

c.               Evaluated theeffectiveness of the registrant’s disclosure controls and procedures andpresented in this report our conclusions about the effectiveness of thedisclosure controls and procedures as of the end of the period covered by thisreport based on such evaluation; and

 

d.              Disclosed inthis report any change in the registrant’s internal control over financialreporting that occurred during the registrant’s most recent fiscal quarter thathas materially affected, or is reasonably likely to materially affect, theregistrant’s internal control over financial reporting; and

 

5.               The registrant’s othercertifying officer and I have disclosed, based on our most recent evaluation ofinternal control over financial reporting, to the registrant’s auditors and theaudit committee of the registrant’s board of directors (or persons performingthe equivalent functions):

 

a.               All significantdeficiencies and material weaknesses in the design or operation of internalcontrol over financial reporting which are reasonable likely to adverselyaffect the registrant’s ability to record, process, summarize and reportfinancial information; and

 

b.              Any fraud,whether or not material, that involves management or other employees who have asignificant role in the registrant’s internal control over financial reporting.

 
| Date: November 9, 2010 | /s/ Anthony R. Fabiano  |
|---------------------------------------|----------------------------------------|
|                                  | Anthony R. Fabiano                     |
|                                  | President and Chief  Executive Officer |

 

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