**EXHIBIT 31.1**

 

CERTIFICATIONOF CHIEF EXECUTIVE OFFICER

 

I, Thomas E. Noonan, Chief Executive Officerand President of Internet Security Systems, Inc., certify that:

 

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

 

2. Based on my knowledge, this quarterlyreport 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 quarterly report;

 

3. Based on my knowledge, the financialstatements, and other financial information included in this quarterly 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 quarterly report;

 

4. Registrant’s other certifying officer andI am responsible for establishing and maintaining disclosure controls and procedures(as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) andinternal control over financial reporting (as defined in Exchange ActRules 13a-15(f) and 15d-15(f) for the Registrant and have:

 

a. designed such disclosure controls andprocedures, or caused such disclosure controls and procedures to be designedunder our supervision, to ensure that material information relating to theRegistrant, including its consolidated subsidiaries, is made known to us byothers within those entities, particularly during the period in which thisquarterly report is being prepared;

 

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; and

 

d. disclosed in this quarterly report anychange in the Registrant’s internal control over financial reporting thatoccurred during Registrant’s third quarter of fiscal 2005 that has materiallyaffected, or is reasonably likely to materially affect, the Registrant’sinternal control over financial reporting; and

 

5. The Registrant’s other certifying officerand I have disclosed, based on our most recent evaluation of internal controlover financial reporting, to Registrant’s auditors and the audit committee ofthe Registrant’s board of directors (or persons performing the equivalentfunctions):

 

a. all significant deficiencies and materialweaknesses in the design or operation of internal control over financialreporting which are reasonably likely to adversely affect the Registrant’sability to record, process, summarize and report financial information; and

 

b. any fraud, whether or not material, thatinvolves 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 |
|             |                                   |
| November 9, 2005 |                                   |

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