<PAGE>   1

    As filed with the Securities and Exchange Commission on January 31, 2001
                                                    Registration No. 333-_______

================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    ---------
                                    FORM S-8
                             REGISTRATION STATEMENT
                                      Under
                           The Securities Act of 1933

                                    ---------
                         INTERNET SECURITY SYSTEMS, INC.
             (Exact name of registrant as specified in its charter)

                DELAWARE                                58-2362189
      (State or other jurisdiction           (IRS Employer Identification No.)
   of incorporation or organization)

                               6303 BARFIELD ROAD
                             ATLANTA, GEORGIA 30328
               (Address of principal executive offices) (Zip Code)

                                    ---------
                            1995 STOCK INCENTIVE PLAN
                    (AMENDED AND RESTATED AS OF MAY 24, 2000)
                        1999 EMPLOYEE STOCK PURCHASE PLAN
                     1999 INTERNATIONAL STOCK PURCHASE PLAN
                            (Full title of the Plans)

                                    ---------
                                THOMAS E. NOONAN
                 CHAIRMAN, PRESIDENT AND CHIEF EXECUTIVE OFFICER
                         INTERNET SECURITY SYSTEMS, INC.
                               6303 BARFIELD ROAD
                             ATLANTA, GEORGIA 30328
                     (Name and address of agent for service)
                                 (404) 236-2600
          (Telephone number, including area code, of agent for service)

                                    ---------
                         CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
=================================================================================================================================
                                                                      Proposed              Proposed
        Title of Securities to be            Amount to be         Maximum Offering     Maximum Aggregate         Amount of
                Registered                   Registered(1)        Price per Share        Offering Price       Registration Fee
   -----------------------------------      ----------------      ----------------     -----------------      ----------------
   <S>                                      <C>                   <C>                  <C>                    <C>
   1995 Stock Incentive Plan
   Common Stock, $0.001 par value           3,020,615 shares         $74.35(2)          $224,582,725.20(2)       $56,145.68
   1999 Employee Stock Purchase Plan
   Common Stock, $0.001 par value              90,000 shares         $74.35(2)          $  6,691,500.00(2)       $ 1,672.88
   1999 International Employee Stock
   Purchase Plan
   Common Stock, $0.001 par value              10,000 shares         $74.35(2)          $    743,500.00(2)       $   185.88
                                            3,120,615 shares
                                            ================
   Aggregate Registration Fee                                                                                    $58,004.44
                                                                                                              ================
=================================================================================================================================
</TABLE>

  (1)    This Registration Statement shall also cover any additional shares of
         Common Stock which become issuable under the 1995 Stock Incentive Plan,
         the 1999 Employee Stock Purchase Plan and the 1999 International
         Employee Stock Purchase Plan by reason of any stock dividend, stock
         split, recapitalization or other similar transaction effected without
         the Registrant's receipt of consideration which results in an increase
         in the number of the outstanding shares of Registrant's Common Stock.

  (2)    Calculated solely for purposes of this offering under Rule 457(h) of
         the Securities Act of 1933, as amended, on the basis of the average of
         the high and low selling prices per share of Registrant's Common Stock
         on January 25, 2001, as reported by the Nasdaq National Market.


<PAGE>   2

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3. Incorporation of Documents by Reference

                  Internet Security Systems, Inc. (the "Registrant") hereby
incorporates by reference into this Registration Statement the following
documents previously filed with the Securities and Exchange Commission (the
"Commission"):

         (a)      The Registrant's Annual Report on Form 10-K filed with the
                  Commission on March 30, 2000 for the fiscal year ended
                  December 31, 1999;

         (b)      The Registrant's Quarterly Reports on Form 10-Q filed with the
                  Commission on May 12, 2000, August 14, 2000 and November 14,
                  2000 for the fiscal periods ended March 31, 2000, June 30,
                  2000, and September 30, 2000, respectively;

         (c)      The Registrant's Current Reports on Form 8-K filed with the
                  Commission on January 31, 2000 and October 20, 2000,
                  respectively; and

         (d)      The Registrant's Registration Statement No. 000-23655 on Form
                  8-A filed with the Commission on March 13, 1998, in which are
                  described the terms, rights and provisions applicable to the
                  Registrant's outstanding Common Stock.

                  All reports and definitive proxy or information statements
filed pursuant to Section 13(a), 13(c), 14 or 15(d) of the Securities Exchange
Act of 1934, as amended (the "1934 Act") after the date of this Registration
Statement and prior to the filing of a post-effective amendment which indicates
that all securities offered hereby have been sold or which de-registers all
securities then remaining unsold shall be deemed to be incorporated by reference
into this Registration Statement and to be a part hereof from the date of filing
of such documents. Any statement contained in a document incorporated or deemed
to be incorporated by reference herein shall be deemed to be modified or
superseded for purposes of this Registration Statement to the extent that a
statement contained herein or in any subsequently filed document which also is
deemed to be incorporated by reference herein modifies or supersedes such
statement. Any such statement so modified or superseded shall not be deemed,
except as so modified or superseded, to constitute a part of this Registration
Statement.

Item 4. Description of Securities

                  Not Applicable.

Item 5. Interests of Named Experts and Counsel

                  Not Applicable.

Item 6.  Indemnification of Directors and Officers

                  Subsection (a) of Section 145 of the Delaware General
Corporation Law empowers a corporation to indemnify any person who was or is a
party or is threatened to be made a party to any threatened, pending or
completed action, suit or proceeding whether civil, criminal, administrative or
investigative (other than an action by or in the right of the corporation) by
reason of the fact that he is or was a director, officer, employee or agent of
the corporation, or is or was serving at the request of the corporation as a
director, officer, employee or agent of another corporation, partnership, joint
venture, trust or other enterprise, against expenses (including attorneys'
fees), judgments, fines and amounts paid in settlement actually and reasonably
incurred by him in connection with such action, suit or proceeding if he acted
in good faith and in a manner he reasonably believed to be in or not opposed to
the best interests of the corporation, and, with respect to any criminal action
or proceeding, had no reasonable cause to believe his conduct was unlawful.


                                      II-1
<PAGE>   3

                  Subsection (b) of Section 145 empowers a corporation to
indemnify any person who was or is a party or is threatened to be made a party
to any threatened, pending or completed action or suit by right of the
corporation to procure a judgment in its favor by reason of the fact that such
person acted in any of the capacities set forth above, against expenses
(including attorneys' fees) actually and reasonably incurred by him in
connection with the defense or settlement of such action or suit if he acted in
good faith and in a manner he reasonably believed to be in or not opposed to the
best interests of the corporation, except that no indemnification may be made in
respect to any claim, issue or matter as to which such person shall have been
adjudged to be liable to the corporation unless and only to the extent that the
Court of Chancery or the court in which such action or suit was brought shall
determine upon application that, despite the adjudication of liability but in
view of all the circumstances of the case, such person is fairly and reasonably
entitled to indemnity for such expenses which the Court of Chancery or such
other court shall deem proper.

                  Section 145 further provides that to the extent a director or
officer of a corporation has been successful on the merits or otherwise in the
defense of any such action, suit or proceeding referred to in subsections (a)
and (b) of Section 145 or in the defense of any claim, issue or matter therein,
he shall be indemnified against expenses (including attorneys' fees) actually
and reasonably incurred by him in connection therewith; that the indemnification
provided for by Section 145 shall not be deemed exclusive of any other rights
which the indemnified party may be entitled; that indemnification provided by
Section 145 shall, unless otherwise provided when authorized or ratified,
continue as to a person who has ceased to be a director, officer, employee or
agent and shall inure to the benefit of such person's heirs, executors and
administrators; and empowers the corporation to purchase and maintain insurance
on behalf of a director or officer of the corporation against any liability
asserted against him and incurred by him in any such capacity, or arising out of
his status as such, whether or not the corporation would have the power to
indemnify him against such liabilities under Section 145.

                  Section 102(b)(7) of the Delaware General Corporation Law
provides that a certificate of incorporation may contain a provision eliminating
or limiting the personal liability of a director to the corporation or its
stockholders for monetary damages for breach of fiduciary duty as a director,
provided that such provision shall not eliminate or limit the liability of the
director (i) for any breach of the director's duty of loyalty to the corporation
or its stockholders, (ii) for acts or omissions not in good faith or which
involve intentional misconduct or a knowing violation of law, (iii) under
Section 174 of the Delaware General Corporation Law or (iv) for any transaction
from which the director derived an improper personal benefit.

                  Article V of the Registrant's Restated Certificate of
Incorporation provides that, to the fullest extent permitted by the Delaware
General Corporation Law as the same exists or as it may hereafter be amended, no
director of the Registrant shall be personally liable to the Registrant or its
stockholders for monetary damages for breach of fiduciary duty as a director.

                  Article XI of the Registrant's bylaws further provides that
the Registrant shall, to the fullest extent not prohibited by the Delaware
General Corporation Law, indemnify each of its directors and executive officers,
subject to limitations, if any, set forth in individual contracts with such
directors and executive officers. The Registrant has entered into
indemnification agreements with each of its directors and executive officers
that provide for indemnification and expense advancement to the fullest extent
permitted under the Delaware General Corporation Law.

                  The Registrant has purchased officers' and directors'
liability insurance.

Item 7. Exemption from Registration Claimed

                  Not Applicable.

Item 8. Exhibits


                                      II-2
<PAGE>   4

<TABLE>
<CAPTION>
Exhibit Number        Exhibit
--------------        -------
<S>                   <C>
        4             Instruments Defining the Rights of Stockholders. Reference is made to Registrant's
                      Registration Statement No. 000-23655 on Form 8-A, together with any exhibits thereto, which
                      are incorporated herein by reference pursuant to Item 3(d) to this Registration Statement.
        5             Opinion and consent of Brobeck, Phleger & Harrison LLP.
       23.1           Consent of Ernst & Young LLP, Independent Auditors.
       23.2           Consent of Brobeck, Phleger & Harrison LLP is contained in Exhibit 5.
       24             Power of Attorney. Reference is made to the Signature Page of this Registration Statement.
       99.1           1995 Stock Incentive Plan (Amended and Restated as of May 24, 2000).
       99.2           1999 Employee Stock Purchase Plan.1
       99.3           1999 International Employee Stock Purchase Plan.2
</TABLE>

---------------

(1)      incorporated herein by reference to Exhibit 99.9 to Registrant's
         Registration Statement No. 333-89563 on Form S-8 filed with the
         Commission on October 22, 1999 (the "1999 S-8").

(2)      incorporated herein by reference to Exhibit 99.12 to the 1999 S-8.

Item 9. Undertakings

                  A.       The undersigned Registrant hereby undertakes: (1) to
file, during any period in which offers or sales are being made, a
post-effective amendment to this Registration Statement: (i) to include any
prospectus required by Section 10(a)(3) of the 1933 Act, (ii) to reflect in the
prospectus any facts or events arising after the effective date of this
Registration Statement (or the most recent post-effective amendment thereof)
which, individually or in the aggregate, represent a fundamental change in the
information set forth in this Registration Statement and (iii) to include any
material information with respect to the plan of distribution not previously
disclosed in this Registration Statement or any material change to such
information in this Registration Statement; provided, however, that clauses
(1)(i) and (1)(ii) shall not apply if the information required to be included in
a post-effective amendment by those clauses is contained in periodic reports
filed by the Registrant pursuant to Section 13 or Section 15(d) of the 1934 Act
that are incorporated by reference into this Registration Statement; (2) that
for the purpose of determining any liability under the 1933 Act each such
post-effective amendment shall be deemed to be a new registration statement
relating to the securities offered therein and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof; and
(3) to remove from registration by means of a post-effective amendment any of
the securities being registered which remain unsold at the termination of the
Registrant's 1995 Stock Incentive Plan, the 1999 Employee Stock Purchase Plan
and the 1999 International Employee Stock Purchase Plan.

                  B.       The undersigned Registrant hereby undertakes that,
for purposes of determining any liability under the 1933 Act, each filing of the
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
1934 Act that is incorporated by reference into this Registration Statement
shall be deemed to be a new registration statement relating to the securities
offered therein, and the offering of such securities at that time shall be
deemed to be the initial bona fide offering thereof.

                  C.       Insofar as indemnification for liabilities arising
under the 1933 Act may be permitted to directors, officers or controlling
persons of the Registrant pursuant to the indemnification provisions summarized
in Item 6 or otherwise, the Registrant has been advised that, in the opinion of
the Commission, such indemnification is against public policy as expressed in
the 1933 Act and is, therefore, unenforceable. In the event that a claim for
indemnification against such liabilities (other than the payment by the
Registrant of expenses incurred or paid by a director, officer, or controlling
person of the Registrant in the successful defense of any action, suit or
proceeding) is asserted by such director, officer or controlling person in
connection with the securities being registered, the Registrant will, unless in
the opinion of its counsel the matter has been settled by controlling precedent,
submit to a court of appropriate jurisdiction the question whether such
indemnification by it is against public policy as expressed in the 1933 Act and
will be governed by the final adjudication of such issue.


                                      II-3
<PAGE>   5

                                   SIGNATURES

                  Pursuant to the requirements of the Securities Act of 1933, as
amended, the Registrant certifies that it has reasonable grounds to believe that
it meets all of the requirements for filing on Form S-8, and has duly caused
this Registration Statement to be signed on its behalf by the undersigned,
thereunto duly authorized, in the City of Atlanta, State of Georgia on this 31st
day of January, 2001.

                                INTERNET SECURITY SYSTEMS, INC.


                                By: /s/ Thomas E. Noonan
                                   ---------------------------------------------
                                   Thomas E. Noonan
                                   President and Chief Executive Officer

                                POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS:

                  That the undersigned officers and directors of Internet
Security Systems, Inc., a Delaware corporation, do hereby constitute and appoint
Thomas E. Noonan and Richard Macchia and each of them, the lawful
attorneys-in-fact and agents with full power and authority to do any and all
acts and things and to execute any and all instruments which said attorneys and
agents, and any one of them, determine may be necessary or advisable or required
to enable said corporation to comply with the Securities Act of 1933, as
amended, and any rules or regulations or requirements of the Securities and
Exchange Commission in connection with this Registration Statement. Without
limiting the generality of the foregoing power and authority, the powers granted
include the power and authority to sign the names of the undersigned officers
and directors in the capacities indicated below to this Registration Statement,
to any and all amendments, both pre-effective and post-effective, and
supplements to this Registration Statement, and to any and all instruments or
documents filed as part of or in conjunction with this Registration Statement or
amendments or supplements thereof, and each of the undersigned hereby ratifies
and confirms all that said attorneys and agents, or any one of them, shall do or
cause to be done by virtue hereof. This Power of Attorney may be signed in
several counterparts.

                  IN WITNESS WHEREOF, each of the undersigned has executed this
Power of Attorney as of the date indicated.

                  Pursuant to the requirements of the Securities Act of 1933, as
amended, this Registration Statement has been signed below by the following
persons in the capacities and on the dates indicated.

<TABLE>
<CAPTION>
          SIGNATURE                                TITLE                              DATE
-------------------------------    ---------------------------------------         ----------------
<S>                                <C>                                             <C>


/s/ Thomas E. Noonan               Chairman, President and Chief Executive         January 31, 2001
-------------------------------    Officer (Principal Executive Officer)
Thomas E. Noonan


/s/ Christopher W. Klaus           Chief Technology Officer, Secretary and         January 31, 2001
-------------------------------    Director
Christopher W. Klaus


/s/ Richard Macchia                Vice President and Chief Financial Officer      January 31, 2001
-------------------------------    (Principal Financial and Accounting Officer)
Richard Macchia
</TABLE>


                                      II-4

<PAGE>   6

<TABLE>
<CAPTION>
          SIGNATURE                                TITLE                              DATE
-------------------------------    ---------------------------------------         -----------------
<S>                                <C>                                             <C>


/s/ Richard S. Bodman              Director                                        January 31, 2001
-------------------------------
Richard S. Bodman


/s/ Robert E. Davoli               Director                                        January 31, 2001
-------------------------------
Robert E. Davoli


/s/ Kevin J. O'Connor              Director                                        January 31, 2001
-------------------------------
Kevin J. O'Connor


/s/ Sam Nunn                       Director                                        January 31, 2001
-------------------------------
Sam Nunn


/s/ David N. Strohm                Director                                        January 31, 2001
-------------------------------
David N. Strohm
</TABLE>


                                      II-5

<PAGE>   7

                                  EXHIBIT INDEX

<TABLE>
<CAPTION>
Exhibit Number        Exhibit
--------------        -------
<S>                   <C>
        4             Instruments Defining the Rights of Stockholders. Reference is made to Registrant's
                      Registration Statement No. 000-23655 on Form 8-A, together with any exhibits thereto, which
                      are incorporated herein by reference pursuant to Item 3(d) to this Registration Statement.
        5             Opinion and consent of Brobeck, Phleger & Harrison LLP.
       23.1           Consent of Ernst & Young LLP, Independent Auditors.
       23.2           Consent of Brobeck, Phleger & Harrison LLP is contained in Exhibit 5.
       24             Power of Attorney. Reference is made to the Signature Page of this Registration Statement.
       99.1           1995 Stock Incentive Plan (Amended and Restated as of May 24, 2000).
       99.2           1999 Employee Stock Purchase Plan.1
       99.3           1999 International Employee Stock Purchase Plan.2
</TABLE>

---------------

(1)      incorporated herein by reference to Exhibit 99.9 to Registrant's
         Registration Statement No. 333-89563 on Form S-8 filed with the
         Commission on October 22, 1999 (the "1999 S-8").

(2)      incorporated herein by reference to Exhibit 99.12 to the 1999 S-8.
[{"type": "S-8", "sequence": "1", "filename": "g66597s-8.txt", "description": "INTERNET SECURITY SYSTEMS, INC.", "secsgml_size_bytes": 23763}]
{"company-data": {"conformed-name": "INTERNET SECURITY SYSTEMS INC/GA", "cik": "0001053148", "assigned-sic": "7372", "irs-number": "582362189", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-54670", "film-number": "1520005"}, "business-address": {"street1": "6600 PEACHTREE DUNWOODY RD", "street2": "BLDG 300 SUITE 500", "city": "ATLANTA", "state": "GA", "zip": "30328", "phone": "6784436000"}, "mail-address": {"street1": "6600 PEACHTREE DUNWOODY RD", "street2": "BLDG 300 SUITE 500", "city": "ATLANTA", "state": "GA", "zip": "30328"}, "former-company": {"former-conformed-name": "ISS GROUP INC", "date-changed": "19980116"}}
1

    As filed with the Securities and Exchange Commission on January 31, 2001
                                                    Registration No. 333-_______

================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    ---------
                                    FORM S-8
                             REGISTRATION STATEMENT
                                      Under
                           The Securities Act of 1933

                                    ---------
                         INTERNET SECURITY SYSTEMS, INC.
             (Exact name of registrant as specified in its charter)

                DELAWARE                                58-2362189
      (State or other jurisdiction           (IRS Employer Identification No.)
   of incorporation or organization)

                               6303 BARFIELD ROAD
                             ATLANTA, GEORGIA 30328
               (Address of principal executive offices) (Zip Code)

                                    ---------
                            1995 STOCK INCENTIVE PLAN
                    (AMENDED AND RESTATED AS OF MAY 24, 2000)
                        1999 EMPLOYEE STOCK PURCHASE PLAN
                     1999 INTERNATIONAL STOCK PURCHASE PLAN
                            (Full title of the Plans)

                                    ---------
                                THOMAS E. NOONAN
                 CHAIRMAN, PRESIDENT AND CHIEF EXECUTIVE OFFICER
                         INTERNET SECURITY SYSTEMS, INC.
                               6303 BARFIELD ROAD
                             ATLANTA, GEORGIA 30328
                     (Name and address of agent for service)
                                 (404) 236-2600
          (Telephone number, including area code, of agent for service)

                                    ---------
                         CALCULATION OF REGISTRATION FEE
=================================================================================================================================
                                                                      Proposed              Proposed
        Title of Securities to be            Amount to be         Maximum Offering     Maximum Aggregate         Amount of
                Registered                   Registered(1)        Price per Share        Offering Price       Registration Fee
   -----------------------------------      ----------------      ----------------     -----------------      ----------------
1995 Stock Incentive Plan
   Common Stock, $0.001 par value           3,020,615 shares         $74.35(2)          $224,582,725.20(2)       $56,145.68
   1999 Employee Stock Purchase Plan
   Common Stock, $0.001 par value              90,000 shares         $74.35(2)          $  6,691,500.00(2)       $ 1,672.88
   1999 International Employee Stock
   Purchase Plan
   Common Stock, $0.001 par value              10,000 shares         $74.35(2)          $    743,500.00(2)       $   185.88
                                            3,120,615 shares
                                            ================
   Aggregate Registration Fee                                                                                    $58,004.44
                                                                                                              ================
=================================================================================================================================
(1)    This Registration Statement shall also cover any additional shares of
         Common Stock which become issuable under the 1995 Stock Incentive Plan,
         the 1999 Employee Stock Purchase Plan and the 1999 International
         Employee Stock Purchase Plan by reason of any stock dividend, stock
         split, recapitalization or other similar transaction effected without
         the Registrant's receipt of consideration which results in an increase
         in the number of the outstanding shares of Registrant's Common Stock.

  (2)    Calculated solely for purposes of this offering under Rule 457(h) of
         the Securities Act of 1933, as amended, on the basis of the average of
         the high and low selling prices per share of Registrant's Common Stock
         on January 25, 2001, as reported by the Nasdaq National Market.
2

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3. Incorporation of Documents by Reference

                  Internet Security Systems, Inc. (the "Registrant") hereby
incorporates by reference into this Registration Statement the following
documents previously filed with the Securities and Exchange Commission (the
"Commission"):

         (a)      The Registrant's Annual Report on Form 10-K filed with the
                  Commission on March 30, 2000 for the fiscal year ended
                  December 31, 1999;

         (b)      The Registrant's Quarterly Reports on Form 10-Q filed with the
                  Commission on May 12, 2000, August 14, 2000 and November 14,
                  2000 for the fiscal periods ended March 31, 2000, June 30,
                  2000, and September 30, 2000, respectively;

         (c)      The Registrant's Current Reports on Form 8-K filed with the
                  Commission on January 31, 2000 and October 20, 2000,
                  respectively; and

         (d)      The Registrant's Registration Statement No. 000-23655 on Form
                  8-A filed with the Commission on March 13, 1998, in which are
                  described the terms, rights and provisions applicable to the
                  Registrant's outstanding Common Stock.

                  All reports and definitive proxy or information statements
filed pursuant to Section 13(a), 13(c), 14 or 15(d) of the Securities Exchange
Act of 1934, as amended (the "1934 Act") after the date of this Registration
Statement and prior to the filing of a post-effective amendment which indicates
that all securities offered hereby have been sold or which de-registers all
securities then remaining unsold shall be deemed to be incorporated by reference
into this Registration Statement and to be a part hereof from the date of filing
of such documents. Any statement contained in a document incorporated or deemed
to be incorporated by reference herein shall be deemed to be modified or
superseded for purposes of this Registration Statement to the extent that a
statement contained herein or in any subsequently filed document which also is
deemed to be incorporated by reference herein modifies or supersedes such
statement. Any such statement so modified or superseded shall not be deemed,
except as so modified or superseded, to constitute a part of this Registration
Statement.

Item 4. Description of Securities

                  Not Applicable.

Item 5. Interests of Named Experts and Counsel

                  Not Applicable.

Item 6.  Indemnification of Directors and Officers

                  Subsection (a) of Section 145 of the Delaware General
Corporation Law empowers a corporation to indemnify any person who was or is a
party or is threatened to be made a party to any threatened, pending or
completed action, suit or proceeding whether civil, criminal, administrative or
investigative (other than an action by or in the right of the corporation) by
reason of the fact that he is or was a director, officer, employee or agent of
the corporation, or is or was serving at the request of the corporation as a
director, officer, employee or agent of another corporation, partnership, joint
venture, trust or other enterprise, against expenses (including attorneys'
fees), judgments, fines and amounts paid in settlement actually and reasonably
incurred by him in connection with such action, suit or proceeding if he acted
in good faith and in a manner he reasonably believed to be in or not opposed to
the best interests of the corporation, and, with respect to any criminal action
or proceeding, had no reasonable cause to believe his conduct was unlawful.

                                      II-1
3

                  Subsection (b) of Section 145 empowers a corporation to
indemnify any person who was or is a party or is threatened to be made a party
to any threatened, pending or completed action or suit by right of the
corporation to procure a judgment in its favor by reason of the fact that such
person acted in any of the capacities set forth above, against expenses
(including attorneys' fees) actually and reasonably incurred by him in
connection with the defense or settlement of such action or suit if he acted in
good faith and in a manner he reasonably believed to be in or not opposed to the
best interests of the corporation, except that no indemnification may be made in
respect to any claim, issue or matter as to which such person shall have been
adjudged to be liable to the corporation unless and only to the extent that the
Court of Chancery or the court in which such action or suit was brought shall
determine upon application that, despite the adjudication of liability but in
view of all the circumstances of the case, such person is fairly and reasonably
entitled to indemnity for such expenses which the Court of Chancery or such
other court shall deem proper.

                  Section 145 further provides that to the extent a director or
officer of a corporation has been successful on the merits or otherwise in the
defense of any such action, suit or proceeding referred to in subsections (a)
and (b) of Section 145 or in the defense of any claim, issue or matter therein,
he shall be indemnified against expenses (including attorneys' fees) actually
and reasonably incurred by him in connection therewith; that the indemnification
provided for by Section 145 shall not be deemed exclusive of any other rights
which the indemnified party may be entitled; that indemnification provided by
Section 145 shall, unless otherwise provided when authorized or ratified,
continue as to a person who has ceased to be a director, officer, employee or
agent and shall inure to the benefit of such person's heirs, executors and
administrators; and empowers the corporation to purchase and maintain insurance
on behalf of a director or officer of the corporation against any liability
asserted against him and incurred by him in any such capacity, or arising out of
his status as such, whether or not the corporation would have the power to
indemnify him against such liabilities under Section 145.

                  Section 102(b)(7) of the Delaware General Corporation Law
provides that a certificate of incorporation may contain a provision eliminating
or limiting the personal liability of a director to the corporation or its
stockholders for monetary damages for breach of fiduciary duty as a director,
provided that such provision shall not eliminate or limit the liability of the
director (i) for any breach of the director's duty of loyalty to the corporation
or its stockholders, (ii) for acts or omissions not in good faith or which
involve intentional misconduct or a knowing violation of law, (iii) under
Section 174 of the Delaware General Corporation Law or (iv) for any transaction
from which the director derived an improper personal benefit.

                  Article V of the Registrant's Restated Certificate of
Incorporation provides that, to the fullest extent permitted by the Delaware
General Corporation Law as the same exists or as it may hereafter be amended, no
director of the Registrant shall be personally liable to the Registrant or its
stockholders for monetary damages for breach of fiduciary duty as a director.

                  Article XI of the Registrant's bylaws further provides that
the Registrant shall, to the fullest extent not prohibited by the Delaware
General Corporation Law, indemnify each of its directors and executive officers,
subject to limitations, if any, set forth in individual contracts with such
directors and executive officers. The Registrant has entered into
indemnification agreements with each of its directors and executive officers
that provide for indemnification and expense advancement to the fullest extent
permitted under the Delaware General Corporation Law.

                  The Registrant has purchased officers' and directors'
liability insurance.

Item 7. Exemption from Registration Claimed

                  Not Applicable.

Item 8. Exhibits

                                      II-2
4
Exhibit Number        Exhibit
--------------        -------
4             Instruments Defining the Rights of Stockholders. Reference is made to Registrant's
                      Registration Statement No. 000-23655 on Form 8-A, together with any exhibits thereto, which
                      are incorporated herein by reference pursuant to Item 3(d) to this Registration Statement.
        5             Opinion and consent of Brobeck, Phleger & Harrison LLP.
       23.1           Consent of Ernst & Young LLP, Independent Auditors.
       23.2           Consent of Brobeck, Phleger & Harrison LLP is contained in Exhibit 5.
       24             Power of Attorney. Reference is made to the Signature Page of this Registration Statement.
       99.1           1995 Stock Incentive Plan (Amended and Restated as of May 24, 2000).
       99.2           1999 Employee Stock Purchase Plan.1
       99.3           1999 International Employee Stock Purchase Plan.2
---------------

(1)      incorporated herein by reference to Exhibit 99.9 to Registrant's
         Registration Statement No. 333-89563 on Form S-8 filed with the
         Commission on October 22, 1999 (the "1999 S-8").

(2)      incorporated herein by reference to Exhibit 99.12 to the 1999 S-8.

Item 9. Undertakings

                  A.       The undersigned Registrant hereby undertakes: (1) to
file, during any period in which offers or sales are being made, a
post-effective amendment to this Registration Statement: (i) to include any
prospectus required by Section 10(a)(3) of the 1933 Act, (ii) to reflect in the
prospectus any facts or events arising after the effective date of this
Registration Statement (or the most recent post-effective amendment thereof)
which, individually or in the aggregate, represent a fundamental change in the
information set forth in this Registration Statement and (iii) to include any
material information with respect to the plan of distribution not previously
disclosed in this Registration Statement or any material change to such
information in this Registration Statement; provided, however, that clauses
(1)(i) and (1)(ii) shall not apply if the information required to be included in
a post-effective amendment by those clauses is contained in periodic reports
filed by the Registrant pursuant to Section 13 or Section 15(d) of the 1934 Act
that are incorporated by reference into this Registration Statement; (2) that
for the purpose of determining any liability under the 1933 Act each such
post-effective amendment shall be deemed to be a new registration statement
relating to the securities offered therein and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof; and
(3) to remove from registration by means of a post-effective amendment any of
the securities being registered which remain unsold at the termination of the
Registrant's 1995 Stock Incentive Plan, the 1999 Employee Stock Purchase Plan
and the 1999 International Employee Stock Purchase Plan.

                  B.       The undersigned Registrant hereby undertakes that,
for purposes of determining any liability under the 1933 Act, each filing of the
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
1934 Act that is incorporated by reference into this Registration Statement
shall be deemed to be a new registration statement relating to the securities
offered therein, and the offering of such securities at that time shall be
deemed to be the initial bona fide offering thereof.

                  C.       Insofar as indemnification for liabilities arising
under the 1933 Act may be permitted to directors, officers or controlling
persons of the Registrant pursuant to the indemnification provisions summarized
in Item 6 or otherwise, the Registrant has been advised that, in the opinion of
the Commission, such indemnification is against public policy as expressed in
the 1933 Act and is, therefore, unenforceable. In the event that a claim for
indemnification against such liabilities (other than the payment by the
Registrant of expenses incurred or paid by a director, officer, or controlling
person of the Registrant in the successful defense of any action, suit or
proceeding) is asserted by such director, officer or controlling person in
connection with the securities being registered, the Registrant will, unless in
the opinion of its counsel the matter has been settled by controlling precedent,
submit to a court of appropriate jurisdiction the question whether such
indemnification by it is against public policy as expressed in the 1933 Act and
will be governed by the final adjudication of such issue.

                                      II-3
5

                                   SIGNATURES

                  Pursuant to the requirements of the Securities Act of 1933, as
amended, the Registrant certifies that it has reasonable grounds to believe that
it meets all of the requirements for filing on Form S-8, and has duly caused
this Registration Statement to be signed on its behalf by the undersigned,
thereunto duly authorized, in the City of Atlanta, State of Georgia on this 31st
day of January, 2001.

                                INTERNET SECURITY SYSTEMS, INC.

                                By: /s/ Thomas E. Noonan
                                   ---------------------------------------------
                                   Thomas E. Noonan
                                   President and Chief Executive Officer

                                POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS:

                  That the undersigned officers and directors of Internet
Security Systems, Inc., a Delaware corporation, do hereby constitute and appoint
Thomas E. Noonan and Richard Macchia and each of them, the lawful
attorneys-in-fact and agents with full power and authority to do any and all
acts and things and to execute any and all instruments which said attorneys and
agents, and any one of them, determine may be necessary or advisable or required
to enable said corporation to comply with the Securities Act of 1933, as
amended, and any rules or regulations or requirements of the Securities and
Exchange Commission in connection with this Registration Statement. Without
limiting the generality of the foregoing power and authority, the powers granted
include the power and authority to sign the names of the undersigned officers
and directors in the capacities indicated below to this Registration Statement,
to any and all amendments, both pre-effective and post-effective, and
supplements to this Registration Statement, and to any and all instruments or
documents filed as part of or in conjunction with this Registration Statement or
amendments or supplements thereof, and each of the undersigned hereby ratifies
and confirms all that said attorneys and agents, or any one of them, shall do or
cause to be done by virtue hereof. This Power of Attorney may be signed in
several counterparts.

                  IN WITNESS WHEREOF, each of the undersigned has executed this
Power of Attorney as of the date indicated.

                  Pursuant to the requirements of the Securities Act of 1933, as
amended, this Registration Statement has been signed below by the following
persons in the capacities and on the dates indicated.
SIGNATURE                                TITLE                              DATE
-------------------------------    ---------------------------------------         ----------------
/s/ Thomas E. Noonan               Chairman, President and Chief Executive         January 31, 2001
-------------------------------    Officer (Principal Executive Officer)
Thomas E. Noonan

/s/ Christopher W. Klaus           Chief Technology Officer, Secretary and         January 31, 2001
-------------------------------    Director
Christopher W. Klaus

/s/ Richard Macchia                Vice President and Chief Financial Officer      January 31, 2001
-------------------------------    (Principal Financial and Accounting Officer)
Richard Macchia
II-4
6
SIGNATURE                                TITLE                              DATE
-------------------------------    ---------------------------------------         -----------------
/s/ Richard S. Bodman              Director                                        January 31, 2001
-------------------------------
Richard S. Bodman

/s/ Robert E. Davoli               Director                                        January 31, 2001
-------------------------------
Robert E. Davoli

/s/ Kevin J. O'Connor              Director                                        January 31, 2001
-------------------------------
Kevin J. O'Connor

/s/ Sam Nunn                       Director                                        January 31, 2001
-------------------------------
Sam Nunn

/s/ David N. Strohm                Director                                        January 31, 2001
-------------------------------
David N. Strohm
II-5
7

                                  EXHIBIT INDEX
Exhibit Number        Exhibit
--------------        -------
4             Instruments Defining the Rights of Stockholders. Reference is made to Registrant's
                      Registration Statement No. 000-23655 on Form 8-A, together with any exhibits thereto, which
                      are incorporated herein by reference pursuant to Item 3(d) to this Registration Statement.
        5             Opinion and consent of Brobeck, Phleger & Harrison LLP.
       23.1           Consent of Ernst & Young LLP, Independent Auditors.
       23.2           Consent of Brobeck, Phleger & Harrison LLP is contained in Exhibit 5.
       24             Power of Attorney. Reference is made to the Signature Page of this Registration Statement.
       99.1           1995 Stock Incentive Plan (Amended and Restated as of May 24, 2000).
       99.2           1999 Employee Stock Purchase Plan.1
       99.3           1999 International Employee Stock Purchase Plan.2
---------------

(1)      incorporated herein by reference to Exhibit 99.9 to Registrant's
         Registration Statement No. 333-89563 on Form S-8 filed with the
         Commission on October 22, 1999 (the "1999 S-8").

(2)      incorporated herein by reference to Exhibit 99.12 to the 1999 S-8.