**EXHIBIT31.1**

CERTIFICATION OF CHIEF EXECUTIVE OFFICER

I, ThomasE. Noonan, Chief Executive Officer and President of Internet SecuritySystems, Inc., certify that:

1. I have reviewed this quarterly report onForm 10-Q of Internet Security Systems, Inc. (the “Registrant”);

2. Basedon my knowledge, this quarterly report does not contain any untrue statement ofa material fact or omit to state a material fact necessary to make thestatements made, in light of the circumstances under which such statements weremade, not misleading with respect to the period covered by this quarterlyreport;

3. Basedon my knowledge, the financial statements, and other financial informationincluded in this quarterly report, fairly present in all material respects thefinancial condition, results of operations and cash flows of the Registrant asof, and for, the periods presented in this quarterly report;

4.Registrant’s other certifying officer and I am responsible for establishing andmaintaining disclosure 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) and15d-15(f) for the Registrant and have:

a.  designed such disclosure controls and procedures, or caused suchdisclosure controls and procedures to be designed under our supervision, toensure that material information relating to the Registrant, including itsconsolidated subsidiaries, is made known to us by others within those entities,particularly during the period in which this quarterly report is beingprepared;b.  designed such internal control overfinancial reporting, or caused such internal control over financial reportingto be designed under our supervision, to provide reasonable assurance regardingthe reliability of financial reporting and the preparation of financialstatements for external purposes in accordance with generally acceptedaccounting principles;c.  evaluated the effectiveness of theRegistrant’s disclosure controls and procedures and presented in this quarterlyreport our conclusions about the effectiveness of the disclosure controls andprocedures, as of the end of the period covered by this quarterly report basedon such evaluation; andd.  disclosed in this quarterly report anychange in the Registrant’s internal control over financial reporting thatoccurred during Registrant’s second quarter of fiscal 2006 that has materiallyaffected, or is reasonably likely to materially affect, the Registrant’sinternal control over financial reporting; and

5. TheRegistrant’s other certifying officer and I have disclosed, based on our mostrecent evaluation of internal control over financial reporting, to Registrant’sauditors and the audit committee of the Registrant’s board of directors (orpersons performing the equivalent functions):

a.  all significant deficiencies and material weaknesses in the designor operation of internal control over financial reporting which are reasonablylikely to adversely affect the Registrant’s ability to record, process,summarize and report financial information; andb.  any fraud, whether or not material,that involves management or other employees who have a significant role inRegistrant’s internal control over financial reporting.
|                | /s/ THOMAS E. NOONAN                  |   |
|----------------|---------------------------------------|--------|
|           | Thomas E. Noonan                      |   |
|           | Chief Executive Officer and President |   |
|           |                                  |   |
| August 4, 2006 |                                  |   |

 

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