**Exhibit31.1**

WrittenCertification of Chief Executive Officer

I, James J. Leto, certifythat:

1.  I have reviewed this quarterly report on Form10-Q of GTSI Corp.;

2.  Based on my knowledge, this report does notcontain any untrue statement of a material fact or omit to state a materialfact necessary to make the statements made, in light of the circumstances underwhich such statements were made, not misleading with respect to the periodcovered by this report;

3.  Based on my knowledge, the financial statementsand other financial information included in this report, fairly present in allmaterial respects the financial condition, results of operations and cash flowsof the registrant as of, and for, the periods presented in this report;

4.  The registrant’s other certifying officer andI are responsible for establishing and maintaining disclosure controls andprocedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) andinternal control over financial reporting (as defined in Exchange Act Rules13a-15(f) and 15d-15(f)), for the registrant and have:

a.               Designedsuch disclosure 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.              Designedsuch internal control over financial reporting, or caused such internal controlover financial reporting to be designed under our supervision, to providereasonable assurance regarding the reliability of financial reporting and thepreparation of financial statements for external purposes in accordance withgenerally accepted accounting principles;

c.               Evaluatedthe effectiveness 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.              Disclosedin this 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 reasonable likely to materially affect, theregistrants’ internal control over financial reporting; and

5.  The registrant’s other certifying officer andI have disclosed, based upon our most recent evaluation of internal controlover financial reporting, to the registrant’s auditors and the audit committeeof the registrant’s board of directors:

a.               Allsignificant deficiencies and material weaknesses in the design or operation ofinternal control over financial reporting which are reasonably likely toadversely affect the registrant’s ability to record, process, summarize andreport financial information; and

b.              Anyfraud, whether or not material, that involves management or other employees whohave a significant role in the registrant’s internal control over financialreporting.

Date:       May 15, 2007
| /s/ JAMES J. LETO |                                  |
|-------------------|---------------------------------------|
|              | James J. Leto                         |
|              | President and Chief Executive Officer |
|                   |                                       |  |

 

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