SEPARATION AGREEMENT AND FULL AND COMPLETE RELEASE

EXHIBIT 10.13

SEPARATION AGREEMENT

AND

FULL AND COMPLETE RELEASE

This Separation Agreement and Full and Complete Release ("Agreement") is entered into between H. Douglas Johns ("Executive") and Internet Security Systems, Inc. , a Delaware corporation (together with its subsidiary companies, the "Company").

Whereas, the Company and Executive desire to agree upon the separation of Executive from the Company effective January 2, 2007 ("Separation Date"); and

Whereas, the Company and Executive have previously entered into an Indemnity Agreement dated 14 July 2003, a Retention Agreement dated 9 July 2003, and an Agreement on Confidentiality, Work Product and Non-Solicitation dated 1 September 2002 (the "Preexisting Agreements").

Whereas, the Executive has consulted with an attorney and has relied upon the advice of his attorney in signing this Agreement.

Now, therefore, in consideration for payments and benefits provided by the Company as set forth in this Agreement, the sufficiency of which is hereby acknowledged, Executive and the Company agree as follows:

1. Fixed Term Employment.
2. 1. Executive's employment with the Company shall terminate on the Separation Date. Following December 31, 2005 , Executive will begin part-time employment which will continue through the Separation Date. Compensation and benefits will cease upon close of business on the Separation Date. Executive will execute a release in substantially the same form as contained in this Agreement on the Separation Date (excluding the Indemnity Agreement and the Confidentiality, Ownership and Non-Competition Agreement).
   2. During part-time employment, Executive's compensation will be at the rate of $18,150 per month. Medical benefits will also continue during this period. Other employee benefits will apply only as provided in the Company's benefits plans for part-time employees. After the Separation Date, Executive will not be entitled to any further compensation or benefits or severance payments. For the avoidance of doubt, Executive will be eligible for his full 2005 annual and quarterly bonuses as indicated in his current compensation plan for 2005, subject to attainment of applicable performance targets. During part-time employment through the Separation Date, only salary as stated above will be payable, i.e. no incentive compensation or bonuses are applicable. During part-time employment through the Separation Date no minimum number of hours is intended and availability will be as agreed between the parties.
   3. Executive will report to the Chief Executive Officer and perform such responsibilities as the Chief Executive Officer may reasonably assign, consistent with current responsibilities. If Executive elects to leave the Company voluntarily and begins a full-time senior officer position at another company prior to the Separation Date, then part-time employment will terminate, compensation and benefits will cease, and equity incentives such as stock options and restricted stock will cease vesting. This Agreement is for the personal services of Executive. Executive shall receive all payments and other benefits to which Executive is entitled under this Agreement through the Separation Date, unless Executive's employment terminates prior to the Separation Date for Cause, due to death or disability, or as otherwise provided in this Agreement, in which event compensation and benefits will cease upon employment termination. "Cause" means the commission of any act of fraud, embezzlement or dishonesty, any unauthorized use or disclosure by such person of confidential information or trade secrets of the Company or any affiliated company, or any other intentional violation of the Company's Code of Conduct by Executive adversely affecting the business or affairs of the Company or any parent or subsidiary corporation in a material manner.
   4. Equity incentives, such as stock options and restricted stock, will continue to vest according to the Company's incentive stock plans through the Separation Date. Under the Company's incentive stock plans, Executive will have 90 days after the Separation Date to exercise vested stock options.
   5. Provided Executive's part-time employment status continues to January 2, 2007 and for Executive's covenant not to compete with the Company, as provided in this paragraph, the Company agrees that the remaining 12,500 shares of restricted stock granted to Executive on January 27, 2004 will fully vest on January 2, 2007 instead of January 27, 2007. Executive covenants and agrees that from the date of this Agreement until one year following the Separation Date, Executive will not (whether on his own behalf or on behalf of any person or entity other than the Company) hire or solicit for hire any employee of the Company, or engage in or become involved in a business that directly competes with the Company in any line of business in which it is engaged as of the date of this Agreement. A list of currently competing entities has been furnished by the Company to Executive contemporaneously with the execution and delivery of this Agreement. The parties acknowledge that other businesses may have incidental activities that may compete with a business line of the Company and this covenant is not intended to prohibit employment with a business (not identified on the list) who's primary business is not competitive with the business of the Company, provided that Executive is not actively involved or directly responsible for the incidental activity that competes. This covenant does not prohibit investment (whether directly or through public or private investment funds) in securities of any entity that may compete with the Company, provided such investment does not exceed 5% of the equity securities of such entit