<PAGE>   1





     As filed with the Securities and Exchange Commission on March 25, 1997
                                Registration No.
================================================================================
       
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

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

                                   ILOG S.A.
             (Exact name of Registrant as specified in its charter)

<TABLE>
              <S>                                                                       <C>
                   The Republic of France                                                                 None
                   ----------------------                                                  -----------------------------------
                (State or other Jurisdiction                                               (I.R.S. Employer Identification No.)
              of incorporation or Organization)                                                       
</TABLE>
                    9, rue de Verdun, 94253 Gentilly, France
                               (33-1) 49 08 35 00
   (Address, including zip code, of Registrant's principal executive offices)

                           The 1989 Stock Option Plan
                           The 1992 Stock Option Plan
                           The 1996 Stock Option Plan
                1996 International Employee Stock Purchase Plan
                       1996 French Employee Savings Plan

                           (Full title of the plans)


                                 Edouard Efira
                                   ILOG, Inc.
                              1901 Landings Drive
                            Mountain View, CA 94043
                                 (415) 390-9000
                (Name, address, and telephone number, including
                       area code, of agent for service)


                                   Copies to:
                            Francis S. Currie, Esq.
                             John T. Sheridan, Esq.
                        Wilson Sonsini Goodrich & Rosati
                            Professional Corporation
                               650 Page Mill Road
                              Palo Alto, CA 94304
                                 (415) 493-9300

                                     
<PAGE>   2



                        CALCULATION OF REGISTRATION FEE
<TABLE>
<CAPTION>                                                           Proposed            Proposed
                 Title of                                            Maximum             Maximum
                Securities                        Amount            Offering            Aggregate 
                  to be                           to be               Price              Offering               Amount of
                Registered                      Registered         Per Share (1)           Price            Registration Fee
             ----------------                  ------------       ---------------     ----------------      ----------------
 <S>                                           <C>                     <C>              <C>                       <C>
 Ordinary Shares, nominal value four
 French francs per share . . . . . . . .           19,375(2)           $0.20(3)            $3,875.00(4)              $1.17
 
 Ordinary Shares, nominal value four
 French francs per share . . . . . . . .          372,189(5)           $1.79(3)          $666,218.31(6)            $201.88
 

 Ordinary Shares, nominal value four
 French francs per share . . . . . . . .            2,621(7)           $7.36(8)           $19,290.56                 $5.85
  
 Ordinary Shares, nominal value four
 French francs per share . . . . . . . .          792,363(9)           $4.33(3)        $3,430,931.79(10)         $1,039.67
 

 Ordinary Shares, nominal value four
 French francs per share . . . . . . . .          507,637(11)          $7.36(8)        $3,736,208.32             $1,132.18


 Ordinary Shares, nominal value four
 French francs per share . . . . . . . .          150,000(12)          $7.36(8)           $1,104,000               $334.54


 Ordinary Shares, nominal value four
 French francs per share . . . . . . . .           150,000(13)         $7.36(8)           $1,104,000               $334.54


                                             1,994,185 Shares                         $10,064,523.98             $3,049.83
 TOTAL
</TABLE>

(1) Amounts represented on an as converted basis from French francs to U.S.
    dollars. The Noon Buying Rate for the French franc used  for such conversion
    was 5.71 francs per U.S. dollar on March 20, 1997.

(2) For the sole purpose of calculating the registration fee, the number of
    shares to be registered under this Registration Statement has been broken 
    down into subtotals. This subtotal represents the 19,375 shares issuable 
    upon exercise of outstanding options (options that have been granted as  
    of the date of this registration Statement) issued under the 1989 Stock 
    Option Plan.

(3) Estimated in accordance with Rule 457(h) under the Securities Act of
    1933 solely for the purpose of calculating the total registration
    fee.  Computation based on the weighted average exercise price (rounded to
    the nearest cent) at which the options whose exercise will result  in the
    issuance of the shares being registered may be exercised.

(4) Calculated in accordance with Rule 457(h) based on the aggregate
    exercise price for all presently outstanding options described in Note 1
    above.

(5) This subtotal represents the 372,189 shares issuable upon exercise of       
    outstanding options (options that have been granted as of the date of this
    registration Statement) issued under the 1992 Stock Option Plan.

(6) Calculated in accordance with Rule 457(h) based on the aggregate
    exercise price for all presently outstanding options described in Note 5
    above.

(7) This sub-total represents the sum of shares issuable upon exercise of       
    options that have been reserved for issuance but have not been granted under
    the 1992 Stock Option Plan.

(8) Estimated in accordance with Rule 457(h) under the Securities Act of
    1933 solely for the purpose of calculating the registration fee. The
    computation is based upon the closing price of the Company's shares as
    reported on the Nasdaq National Market on March 21, 1997 because the price
    at which will be granted in the future  may be exercised is not currently
    determinable.

(9) This subtotal represents the 792,363 shares issuable upon exercise of       
    outstanding options (options that have been granted as of the date of this
    registration Statement) issued under the 1996 Stock Option Plan.

(10) Calculated in accordance with Rule 457(h) based on the aggregate
    exercise price for all presently outstanding options described in Note 9
    above.



                                      -2-
<PAGE>   3
(11) This subtotal represents the sum of shares issuable upon exercise of
     options that have been reserved for issuance but have not been granted 
     under the 1996 Stock Option Plan.

(12) This subtotal reflects shares issuable upon exercise of options to be
     granted under the 1996 International Employee Stock Purchase Plan.

(13) This subtotal reflects shares issuable upon exercise of options to be
     granted under the 1996 French Employee Savings Plan.





                                     -3-
<PAGE>   4
                                    PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT


Item 3.  Incorporation of Documents by Reference.

                 There are hereby incorporated by reference the following
documents and information heretofore filed with the Securities and Exchange
Commission (the "Commission"):

         Item 3(a).

                 The Company's Registration Statement on Form F-1 (file No.
333-6322) under the Securities Act of 1933, as amended (the "Securities Act"),
which was declared effective on February 13, 1997.

         Item 3(b).

         Not Applicable

         Item 3(c).

                 The description of Registrant's Ordinary Shares to be offered
hereby contained in the Company's Registration Statement on Form F-1, as
declared effective by the Commission on February 13, 1997, filed pursuant to
Section 12 of the Exchange Act and any amendment or report filed for the
purpose of updating such description.

                 All documents, reports and definitive proxy or information
statements subsequently filed by Registrant pursuant to Sections 13(a), 13(c),
14 or 15(d) of the Exchange Act, prior to the filing of a post-effective
amendment which indicates that all securities offered have been sold or which
deregisters all securities then remaining unsold, shall be deemed to be
incorporated by reference in this registration statement and to be part hereof
from the date of filing such documents.

Item 4.  Description of Securities.

                 Not applicable.

Item 5.  Interests of Named Experts and Counsel.

                 Not applicable.





                                     -4-

<PAGE>   5
Item 6.  Indemnification of Directors and Officers.

                 French Law prohibits the Company from entering into
indemnification agreements with its directors and officers providing for
limitations on personal liability for damages and other costs and expenses that
may be incurred by directors and officers arising out of or related to acts or
omissions in such capacity. French Law also prohibits the statuts of the
Company from providing for limitation of liability of a member of the Board of
Directors. Generally, under French Law, directors and officers will not be held
personally liable for decisions taken diligently and in corporate interest of
the Company.

         The Shareholders of the Company have authorized the Company to make an
offer to each of its directors, officers and other members of senior management
designated by the Board of Directors pursuant to which the Company will commit
itself to contract for and maintain liability insurance against liabilities
that may be incurred by such persons in their respective capacities, including
liabilities that may be incurred under the U.S. federal and state securities
laws, subject to certain limitations. The Company believes that entering into
such agreements and maintaining appropriate liability insurance for its
directors and officers will assist the Company in attracting and retaining
qualified individuals to serve as directors and officers.

Item 7.  Exemption from Registration Claimed.

                 Not applicable.

Item 8.  Exhibits.

<TABLE>
<CAPTION>
                 Exhibit
                 Number                    Document
                 -------                   --------
                   <S>            <C>
                    4.1(a)*       The 1989 Stock Option Plan
                    4.1(b)*       The 1992 Stock Option Plan
                    4.1(c)*       The 1996 Stock Option Plan
                    4.1(d)*       1996 International Employee Stock Purchase Plan
                    4.1(e)*       1996 French Employee Savings Plan
                    5.1           Opinion of Giroux, Buhagiar & Associes
                   23.1           Consent of Independent Auditors
                   23.2           Consent of Counsel (contained in Exhibit 5.1)
                   24.1           Power of Attorney (see page II-4)
</TABLE>
___________________

* Incorporated by reference to exhibits 10.1, 10.2, 10.3, 10.4 and 10.5
respectively, filed with the Company's Registration Statement on Form F-1 (file
No. 333-6322), which was declared effective on February 13, 1997.



                                      -5-

<PAGE>   6
  Item 9.        Undertakings.

                 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 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.

                 (2)      That, for the purpose of determining any liability
                          under the Securities 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.

                 (3)      To remove from registration by means of
                          post-effective amendment any of the securities being
                          registered which remain unsold at the termination of
                          the offering.

                 The undersigned Registrant hereby undertakes that, for
purposes of determining any liability under the Securities Act, each filing of
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Exchange Act (and, where applicable, each filing of an employee benefit plan's
annual report pursuant to Section 15(d) of the Exchange Act) that is
incorporated by reference in 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.

                 Insofar as indemnification for liabilities arising under the
Securities Act may be permitted to directors, officers and controlling persons
of the registrant pursuant to the foregoing provisions, or otherwise, the
registrant has been advised that in the opinion of the Securities and Exchange
Commission such indemnification is against public policy as expressed in the
Securities 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
Securities Act and will be governed by the final adjudication of such issue.




                                     -6-

<PAGE>   7
                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, as amended,
the Registrant, ILOG S.A., 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 Gentilly, Republic of France, on this
24th day of March, 1997.

                                        ILOG S.A.

                                        By:   /s/ Pierre Haren          
                                              --------------------------------
                                              President and Chief 
                                              Executive Officer


                               POWER OF ATTORNEY

         KNOW ALL PERSONS BY THESE PRESENTS, that each such person whose
signature appears below constitutes and appoints, jointly and severally, Pierre
Haren and Roger D. Friedberger, his or her attorneys-in-fact, each with the
power of substitution, for him or her in any and all capacities, to sign any
amendments to this Registration Statement on Form S-8 (including post-effective
amendments), and to file the same, with all exhibits thereto, and other
documents in connection therewith, with the Securities and Exchange Commission,
hereby ratifying and confirming all that each of said attorneys-in-fact, or his
substitute or substitutes, may do or cause to be done by virtue hereof.

         Pursuant to the requirements of the Securities Act of 1933, as
amended, this Registration Statement on Form S-8 has been signed by the
following persons in the capacities and on the dates indicated.

<TABLE>
<CAPTION>
                   Signature                                       Title                              Date
-------------------------------------------     ---------------------------------------- 
          <S>                                   <C>                                           <C>    <C>

               /s/ Pierre Haren                 Chairman, President and Chief Executive       March  24, 1997
--------------------------------------------    Officer
               Pierre Haren

           /s/ Roger D. Friedberger             Chief Financial Officer                       March  24, 1997
--------------------------------------------
              Roger D. Friedberger
                               
                /s/ Francois Bussac             Principal Accounting Officer                  March  24, 1997
 --------------------------------------------                                                                
                  Francois Bussac
    
              /s/ Philippe Claude               Director                                      March  24, 1997
---------------------------------------------                                             
                 Philippe Claude

               /s/ Marc Fourrier                Director                                      March  24, 1997
---------------------------------------------
                 Marc Fourrier

          /s/ Jean-Francois Abramatic           Director                                      March  24, 1997
 --------------------------------------------                                                                
            Jean-Francois Abramatic

               /s/ Albert Gabizon               Director                                      March  24, 1997
 --------------------------------------------                                                                
                   Albert Gabizon

</TABLE>




                                      -7-
<PAGE>   8
<TABLE>
<CAPTION>
                   Signature                                       Title                              Date
-------------------------------------------     ---------------------------------------- 
          <S>                                   <C>                                           <C>    <C>

                 /s/ Fredric Harman             Director                                      March  24, 1997
 --------------------------------------------                                                                
                     Fredric Harman  

                  /s/ Edouard Efira             Authorized Representative in the U.S.         March  24, 1997
 --------------------------------------------                                                                
                 Edouard Efira
</TABLE>


                                             -8-
<PAGE>   9






                       SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549



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

                                    EXHIBITS

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


                       Registration Statement on Form S-8


                                   ILOG S.A.


                                 March 25, 1997
<PAGE>   10
                                 EXHIBIT INDEX

             Exhibit
               No.                  Document

              4.1(a)*       The 1989 Stock Option Plan
              4.1(b)*       The 1992 Stock Option Plan
              4.1(c)*       The 1996 Stock Option Plan
              4.1(d)*       1996 International Employee Stock Purchase Plan
              4.1(e)*       1996 French Employee Savings Plan
              5.1           Opinion of Giroux, Buhagiar & Associes
             23.1           Consent of Independent Auditors
             23.2           Consent of Counsel (contained in Exhibit 5.1)
             24.1           Power of Attorney (see page II-4)
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 21144}]
{"company-data": {"conformed-name": "ILOG SA", "cik": "0001031140", "assigned-sic": "7372", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-23919", "film-number": "97562663"}, "business-address": {"street1": "9 RUE DE VERDUN", "city": "94253 GENTILLY FRANC", "state": "I0", "phone": "01133149083500"}}
1

     As filed with the Securities and Exchange Commission on March 25, 1997
                                Registration No.
================================================================================
       
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

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

                                   ILOG S.A.
             (Exact name of Registrant as specified in its charter)
The Republic of France                                                                 None
                   ----------------------                                                  -----------------------------------
                (State or other Jurisdiction                                               (I.R.S. Employer Identification No.)
              of incorporation or Organization)
9, rue de Verdun, 94253 Gentilly, France
                               (33-1) 49 08 35 00
   (Address, including zip code, of Registrant's principal executive offices)

                           The 1989 Stock Option Plan
                           The 1992 Stock Option Plan
                           The 1996 Stock Option Plan
                1996 International Employee Stock Purchase Plan
                       1996 French Employee Savings Plan

                           (Full title of the plans)

                                 Edouard Efira
                                   ILOG, Inc.
                              1901 Landings Drive
                            Mountain View, CA 94043
                                 (415) 390-9000
                (Name, address, and telephone number, including
                       area code, of agent for service)

                                   Copies to:
                            Francis S. Currie, Esq.
                             John T. Sheridan, Esq.
                        Wilson Sonsini Goodrich & Rosati
                            Professional Corporation
                               650 Page Mill Road
                              Palo Alto, CA 94304
                                 (415) 493-9300
2

                        CALCULATION OF REGISTRATION FEE
Proposed            Proposed
                 Title of                                            Maximum             Maximum
                Securities                        Amount            Offering            Aggregate 
                  to be                           to be               Price              Offering               Amount of
                Registered                      Registered         Per Share (1)           Price            Registration Fee
             ----------------                  ------------       ---------------     ----------------      ----------------
Ordinary Shares, nominal value four
 French francs per share . . . . . . . .           19,375(2)           $0.20(3)            $3,875.00(4)              $1.17
 
 Ordinary Shares, nominal value four
 French francs per share . . . . . . . .          372,189(5)           $1.79(3)          $666,218.31(6)            $201.88
 

 Ordinary Shares, nominal value four
 French francs per share . . . . . . . .            2,621(7)           $7.36(8)           $19,290.56                 $5.85
  
 Ordinary Shares, nominal value four
 French francs per share . . . . . . . .          792,363(9)           $4.33(3)        $3,430,931.79(10)         $1,039.67
 

 Ordinary Shares, nominal value four
 French francs per share . . . . . . . .          507,637(11)          $7.36(8)        $3,736,208.32             $1,132.18

 Ordinary Shares, nominal value four
 French francs per share . . . . . . . .          150,000(12)          $7.36(8)           $1,104,000               $334.54

 Ordinary Shares, nominal value four
 French francs per share . . . . . . . .           150,000(13)         $7.36(8)           $1,104,000               $334.54

                                             1,994,185 Shares                         $10,064,523.98             $3,049.83
 TOTAL
(1) Amounts represented on an as converted basis from French francs to U.S.
    dollars. The Noon Buying Rate for the French franc used  for such conversion
    was 5.71 francs per U.S. dollar on March 20, 1997.

(2) For the sole purpose of calculating the registration fee, the number of
    shares to be registered under this Registration Statement has been broken 
    down into subtotals. This subtotal represents the 19,375 shares issuable 
    upon exercise of outstanding options (options that have been granted as  
    of the date of this registration Statement) issued under the 1989 Stock 
    Option Plan.

(3) Estimated in accordance with Rule 457(h) under the Securities Act of
    1933 solely for the purpose of calculating the total registration
    fee.  Computation based on the weighted average exercise price (rounded to
    the nearest cent) at which the options whose exercise will result  in the
    issuance of the shares being registered may be exercised.

(4) Calculated in accordance with Rule 457(h) based on the aggregate
    exercise price for all presently outstanding options described in Note 1
    above.

(5) This subtotal represents the 372,189 shares issuable upon exercise of       
    outstanding options (options that have been granted as of the date of this
    registration Statement) issued under the 1992 Stock Option Plan.

(6) Calculated in accordance with Rule 457(h) based on the aggregate
    exercise price for all presently outstanding options described in Note 5
    above.

(7) This sub-total represents the sum of shares issuable upon exercise of       
    options that have been reserved for issuance but have not been granted under
    the 1992 Stock Option Plan.

(8) Estimated in accordance with Rule 457(h) under the Securities Act of
    1933 solely for the purpose of calculating the registration fee. The
    computation is based upon the closing price of the Company's shares as
    reported on the Nasdaq National Market on March 21, 1997 because the price
    at which will be granted in the future  may be exercised is not currently
    determinable.

(9) This subtotal represents the 792,363 shares issuable upon exercise of       
    outstanding options (options that have been granted as of the date of this
    registration Statement) issued under the 1996 Stock Option Plan.

(10) Calculated in accordance with Rule 457(h) based on the aggregate
    exercise price for all presently outstanding options described in Note 9
    above.

                                      -2-
3
(11) This subtotal represents the sum of shares issuable upon exercise of
     options that have been reserved for issuance but have not been granted 
     under the 1996 Stock Option Plan.

(12) This subtotal reflects shares issuable upon exercise of options to be
     granted under the 1996 International Employee Stock Purchase Plan.

(13) This subtotal reflects shares issuable upon exercise of options to be
     granted under the 1996 French Employee Savings Plan.

                                     -3-
4
                                    PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.  Incorporation of Documents by Reference.

                 There are hereby incorporated by reference the following
documents and information heretofore filed with the Securities and Exchange
Commission (the "Commission"):

         Item 3(a).

                 The Company's Registration Statement on Form F-1 (file No.
333-6322) under the Securities Act of 1933, as amended (the "Securities Act"),
which was declared effective on February 13, 1997.

         Item 3(b).

         Not Applicable

         Item 3(c).

                 The description of Registrant's Ordinary Shares to be offered
hereby contained in the Company's Registration Statement on Form F-1, as
declared effective by the Commission on February 13, 1997, filed pursuant to
Section 12 of the Exchange Act and any amendment or report filed for the
purpose of updating such description.

                 All documents, reports and definitive proxy or information
statements subsequently filed by Registrant pursuant to Sections 13(a), 13(c),
14 or 15(d) of the Exchange Act, prior to the filing of a post-effective
amendment which indicates that all securities offered have been sold or which
deregisters all securities then remaining unsold, shall be deemed to be
incorporated by reference in this registration statement and to be part hereof
from the date of filing such documents.

Item 4.  Description of Securities.

                 Not applicable.

Item 5.  Interests of Named Experts and Counsel.

                 Not applicable.

                                     -4-
5
Item 6.  Indemnification of Directors and Officers.

                 French Law prohibits the Company from entering into
indemnification agreements with its directors and officers providing for
limitations on personal liability for damages and other costs and expenses that
may be incurred by directors and officers arising out of or related to acts or
omissions in such capacity. French Law also prohibits the statuts of the
Company from providing for limitation of liability of a member of the Board of
Directors. Generally, under French Law, directors and officers will not be held
personally liable for decisions taken diligently and in corporate interest of
the Company.

         The Shareholders of the Company have authorized the Company to make an
offer to each of its directors, officers and other members of senior management
designated by the Board of Directors pursuant to which the Company will commit
itself to contract for and maintain liability insurance against liabilities
that may be incurred by such persons in their respective capacities, including
liabilities that may be incurred under the U.S. federal and state securities
laws, subject to certain limitations. The Company believes that entering into
such agreements and maintaining appropriate liability insurance for its
directors and officers will assist the Company in attracting and retaining
qualified individuals to serve as directors and officers.

Item 7.  Exemption from Registration Claimed.

                 Not applicable.

Item 8.  Exhibits.
Exhibit
                 Number                    Document
                 -------                   --------
4.1(a)*       The 1989 Stock Option Plan
                    4.1(b)*       The 1992 Stock Option Plan
                    4.1(c)*       The 1996 Stock Option Plan
                    4.1(d)*       1996 International Employee Stock Purchase Plan
                    4.1(e)*       1996 French Employee Savings Plan
                    5.1           Opinion of Giroux, Buhagiar & Associes
                   23.1           Consent of Independent Auditors
                   23.2           Consent of Counsel (contained in Exhibit 5.1)
                   24.1           Power of Attorney (see page II-4)
___________________

* Incorporated by reference to exhibits 10.1, 10.2, 10.3, 10.4 and 10.5
respectively, filed with the Company's Registration Statement on Form F-1 (file
No. 333-6322), which was declared effective on February 13, 1997.

                                      -5-
6
  Item 9.        Undertakings.

                 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 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.

                 (2)      That, for the purpose of determining any liability
                          under the Securities 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.

                 (3)      To remove from registration by means of
                          post-effective amendment any of the securities being
                          registered which remain unsold at the termination of
                          the offering.

                 The undersigned Registrant hereby undertakes that, for
purposes of determining any liability under the Securities Act, each filing of
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Exchange Act (and, where applicable, each filing of an employee benefit plan's
annual report pursuant to Section 15(d) of the Exchange Act) that is
incorporated by reference in 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.

                 Insofar as indemnification for liabilities arising under the
Securities Act may be permitted to directors, officers and controlling persons
of the registrant pursuant to the foregoing provisions, or otherwise, the
registrant has been advised that in the opinion of the Securities and Exchange
Commission such indemnification is against public policy as expressed in the
Securities 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
Securities Act and will be governed by the final adjudication of such issue.

                                     -6-
7
                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, as amended,
the Registrant, ILOG S.A., 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 Gentilly, Republic of France, on this
24th day of March, 1997.

                                        ILOG S.A.

                                        By:   /s/ Pierre Haren          
                                              --------------------------------
                                              President and Chief 
                                              Executive Officer

                               POWER OF ATTORNEY

         KNOW ALL PERSONS BY THESE PRESENTS, that each such person whose
signature appears below constitutes and appoints, jointly and severally, Pierre
Haren and Roger D. Friedberger, his or her attorneys-in-fact, each with the
power of substitution, for him or her in any and all capacities, to sign any
amendments to this Registration Statement on Form S-8 (including post-effective
amendments), and to file the same, with all exhibits thereto, and other
documents in connection therewith, with the Securities and Exchange Commission,
hereby ratifying and confirming all that each of said attorneys-in-fact, or his
substitute or substitutes, may do or cause to be done by virtue hereof.

         Pursuant to the requirements of the Securities Act of 1933, as
amended, this Registration Statement on Form S-8 has been signed by the
following persons in the capacities and on the dates indicated.
Signature                                       Title                              Date
-------------------------------------------     ----------------------------------------
/s/ Pierre Haren                 Chairman, President and Chief Executive       March  24, 1997
--------------------------------------------    Officer
               Pierre Haren

           /s/ Roger D. Friedberger             Chief Financial Officer                       March  24, 1997
--------------------------------------------
              Roger D. Friedberger
                               
                /s/ Francois Bussac             Principal Accounting Officer                  March  24, 1997
 --------------------------------------------                                                                
                  Francois Bussac
    
              /s/ Philippe Claude               Director                                      March  24, 1997
---------------------------------------------                                             
                 Philippe Claude

               /s/ Marc Fourrier                Director                                      March  24, 1997
---------------------------------------------
                 Marc Fourrier

          /s/ Jean-Francois Abramatic           Director                                      March  24, 1997
 --------------------------------------------                                                                
            Jean-Francois Abramatic

               /s/ Albert Gabizon               Director                                      March  24, 1997
 --------------------------------------------                                                                
                   Albert Gabizon
-7-
8
Signature                                       Title                              Date
-------------------------------------------     ----------------------------------------
/s/ Fredric Harman             Director                                      March  24, 1997
 --------------------------------------------                                                                
                     Fredric Harman  

                  /s/ Edouard Efira             Authorized Representative in the U.S.         March  24, 1997
 --------------------------------------------                                                                
                 Edouard Efira
-8-
9

                       SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

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

                                    EXHIBITS

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

                       Registration Statement on Form S-8

                                   ILOG S.A.

                                 March 25, 1997
10
                                 EXHIBIT INDEX

             Exhibit
               No.                  Document

              4.1(a)*       The 1989 Stock Option Plan
              4.1(b)*       The 1992 Stock Option Plan
              4.1(c)*       The 1996 Stock Option Plan
              4.1(d)*       1996 International Employee Stock Purchase Plan
              4.1(e)*       1996 French Employee Savings Plan
              5.1           Opinion of Giroux, Buhagiar & Associes
             23.1           Consent of Independent Auditors
             23.2           Consent of Counsel (contained in Exhibit 5.1)
             24.1           Power of Attorney (see page II-4)