<PAGE>   1
      As filed with the Securities and Exchange Commission on May 7, 1998
                                           Registration No. 333-________________
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933



                                 COMBICHEM, INC.
               (Exact name of issuer as specified in its charter)

                DELAWARE                            33-0617379
      (State or other jurisdiction        (IRS Employer Identification No.)
     of incorporation or organization)

                9050 CAMINO SANTA FE, SAN DIEGO, CALIFORNIA 92121
               (Address of principal executive offices) (Zip Code)

                                 COMBICHEM, INC.
                          1997 STOCK INCENTIVE PLAN AND
                        1997 EMPLOYEE STOCK PURCHASE PLAN
                            (Full title of the plans)

                             DR. VICENTE ANIDO, JR.
                      PRESIDENT AND CHIEF EXECUTIVE OFFICER
                                 COMBICHEM, INC.
                              9050 CAMINO SANTA FE
                           SAN DIEGO, CALIFORNIA 92121
                     (Name and address of agent for service)
                                 (619) 530-0484
          (Telephone number, including area code, of agent for service)


                         CALCULATION OF REGISTRATION FEE
<TABLE>
<CAPTION>
================================================================================================================
                                                                                  Proposed            Proposed
   Title of                                                                       Maximum              Maximum
  Securities                               Amount            Offering             Aggregate           Amount of
     to be                                  to be              Price              Offering          Registration
  Registered                            Registered(1)      per Share(2)             Price                Fee
  ----------                            -------------      ------------             -----                ---
<S>                                   <C>                  <C>                 <C>                  <C>         
1997 Stock Incentive Plan
Common Stock, par value               1,072,170 shares        $10.00           $10,721,700           $3,162.90
$0.001 per share

1997 Employee Stock Purchase Plan
Common Stock, par value
$0.001 per share                        150,000 shares        $10.00           $ 1,500,000           $  442.50
================================================================================================================
</TABLE>

(1)  This Registration Statement shall also cover any additional shares of the
     Common Stock which become issuable under the Registrant's 1997 Stock
     Incentive Plan or 1997 Employee Stock Purchase Plan by reason of any stock
     dividend, stock split, recapitalization or other similar transaction
     effected without the receipt of consideration which results in an increase
     in the number of the outstanding shares of the Common Stock of CombiChem,
     Inc.

(2)  Estimated solely for the purpose of computing the amount of the
     registration fee.



<PAGE>   2
                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT


Item 3.  Incorporation of Documents by Reference

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

         (a)      The Registrant's Prospectus filed April 7, 1998 with the
                  Registrant's Registration Statement No. 333-37981 on Form S-1,
                  as amended, under the Securities Act of 1933, as amended (the
                  "1933 Act"), in which there is set forth audited financial
                  statements for the Registrant's fiscal year ended December 31,
                  1997;

         (b)      The Registrant's Registration Statement on Form 8-A filed with
                  the SEC on May 4, 1998 pursuant to Section 12 of the
                  Securities Exchange Act of 1934, as amended (the "1934 Act"),
                  in which there is 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 and 15(d) of 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 deregisters 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

         Section 145 of the Delaware General Corporation Law permits
indemnification of officers and directors of the Company under certain
conditions and subject to certain limitations. Section 145 of the Delaware
General Corporation Law also provides that a corporation has the power to
purchase and maintain insurance on behalf of its officers and directors against
any liability asserted against such person and incurred by him or her in such
capacity, or arising out of his or her status as such, whether or not the
corporation would have the power to indemnify him or her against such liability
under the provisions of Section 145 of the Delaware General Corporation Law.

         Article VII, Section 1 of the Restated Bylaws of the Registrant
provides that the Registrant shall indemnify its directors and executive
officers to the fullest extent not prohibited by the Delaware General
Corporation Law. The rights to indemnify thereunder continue as to a person who
has ceased to be a director, officer, employee or agent and inure to the benefit
of the heirs, executors and administrators of the person. In addition, expenses
incurred by a director or executive officer in defending any civil, criminal,
administrative or investigative action, suit or proceeding by reason of the fact
that he or she is or was a director or officer of the Registrant (or was serving
at



<PAGE>   3
the Registrant's request as a director or officer of another corporation) shall
be paid by the Registrant in advance of the final disposition of such action,
suit or proceeding upon receipt of an undertaking by or on behalf of such
director or officer to repay such amount if it shall ultimately be determined
that he or she is not entitled to be indemnified by the Registrant as authorized
by the relevant section of the Delaware General Corporation Law.

         As permitted by Section 102(b)(7) of the Delaware General Corporation
Law, Article V, Section (A) of the Registrant's Restated Certificate of
Incorporation provides that a director of the Registrant shall not be personally
liable for monetary damages for breach of fiduciary duty as a director, except
for liability (i) for any breach of the director's duty of loyalty to the
Registrant or its stockholders, (ii) for acts or omissions not in good faith or
acts or omissions that 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 any improper personal benefit.

         The Registrant has entered into indemnification agreements with each of
its directors and executive officers. Generally, the indemnification agreements
attempt to provide the maximum protection permitted by Delaware law as it may be
amended from time to time. Moreover, the indemnification agreements provide for
certain additional indemnification. Under such additional indemnification
provisions, however, an individual will not receive indemnification for
judgments, settlements or expenses if he or she is found liable to the
Registrant (except to the extent the court determines he or she is fairly and
reasonably entitled to indemnity for expenses), for settlements not approved by
the Registrant or for settlements and expenses if the settlement is not approved
by the court. The indemnification agreements provide for the Registrant to
advance to the individual any and all reasonable expenses (including legal fees
and expenses) incurred in investigating or defending any such action, suit or
proceeding. In order or receive an advance of expenses, the individual must
submit to the Registrant copies of invoices presented to him or her for such
expenses. Also, the individual must repay such advances upon a final judicial
decision that he or she is not entitled to indemnification.

         The Registrant has purchased directors' and officers' liability
insurance. The Registrant intends to enter into additional indemnification
agreements with each of its directors and executive officers to effectuate these
indemnity provisions.


Item 7.  Exemption from Registration Claimed

         Not Applicable.



                                      II-2.
<PAGE>   4
Item 8.  Exhibits

<TABLE>
<CAPTION>
    Number   Exhibit
    ------   -------
<S>          <C>
     4.1     Instruments Defining Rights of Stockholders.  Reference is made to Registrant's Registration
             Statement on Form 8-A, filed on May 4, 1998, and all exhibits thereto which are incorporated herein
             by reference pursuant to Item 3(b).
     5.1     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.
    24.1     Power of Attorney.  Reference is made to page II-5 of this Registration Statement.
*   99.1     1997 Stock Incentive Plan (Exhibit 10.44).
+   99.2     Form of Notice of Grant of Stock Option (Exhibit 10.48).
+   99.3     Form of Stock Option Agreement (Exhibit 10.49).
+   99.4     Form of Addendum to Stock Option Agreement (Involuntary Termination Following Corporate
             Transaction/Change in Control) (Exhibit 10.50).
+   99.5     Form of Addendum to Stock Option Agreement (Limited Stock Appreciation Right)
             (Exhibit 10.51)
+   99.6     Form of Stock Issuance Agreement (Exhibit 10.52).
+   99.7     Form of Addendum to Stock Issuance Agreement (Involuntary Termination Following
             Corporate Transaction/Change in Control) (Exhibit 10.53).
+   99.8     Form of Notice of Grant of Automatic Stock Option (Initial Grant) (Exhibit 10.54).
+   99.9     Form of Notice of Grant of Automatic Stock Option (Annual Grant) (Exhibit 10.55).
+   99.10    Form of Automatic Stock Option Agreement (Exhibit 10.56).
*   99.11    1997 Employee Stock Purchase Plan (Exhibit 10.45).
+   99.12    Form of Stock Purchase Agreement(Exhibit 10.57).
</TABLE>

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

*   These exhibits were previously filed as part of, and are hereby incorporated
    by reference to, the same numbered exhibit (except as otherwise noted) filed
    with the Registrant's Registration Statement on Form S-1 (Commission No.
    333-37981) initially filed on October 15, 1997, as amended.

+   These exhibits were previously filed as part of, and are hereby incorporated
    by reference to, the same numbered exhibit (except as otherwise noted) filed
    with the Registrant's Amendment No. 2 to Registration Statement on Form S-1
    (Commission No. 333-37981) initially filed on December 3, 1997, as amended.

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 paragraphs 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



                                      II-3.
<PAGE>   5
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 1997 Stock Incentive Plan
and 1997 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 foregoing provisions, or otherwise, the Registrant
has been advised that, in the opinion of the SEC, 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-4.
<PAGE>   6
                                   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 San Diego, State of California, on this 7th day
of May, 1998.

                                        COMBICHEM, INC.


                                        By: /s/ Vicente Anido, Jr., Ph.D.
                                           --------------------------------
                                           Vicente Anido, Jr., Ph.D.
                                           President, Chief Executive Officer 
                                           and Director (Principal Executive 
                                           Officer)


                                POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS:

         That the undersigned officers and directors of CombiChem, Inc., a
Delaware corporation, do hereby constitute and appoint Vicente Anido, Jr., Ph.D.
and Karin Eastham, and each of them, with full power of substitution and
resubstitution, 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 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 the undersigned
hereby ratifies and confirms that said attorneys and agents, each acting alone,
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/ Pierre R. Lamond                        Chairman of the Board and Director          May 7, 1998
------------------------------------
Pierre R. Lamond
</TABLE>



                                      II-5.
<PAGE>   7
<TABLE>
<CAPTION>
Signature                                   Title                                               Date
---------                                   -----                                               ----
<S>                                         <C>                                                 <C>
/s/ Vicente Anido, Jr., Ph.D.               President, Chief Executive Officer                  May 7, 1998
-----------------------------------         and Director (Principal Executive Officer)
Vicente Anido, Jr., Ph.D.          


/s/ Peter L. Myers, Ph.D.                   Vice President, Chief Scientific Officer,           May 7, 1998
-----------------------------------         Chief Operating Officer and Director
Peter L. Myers, Ph.D.              


/s/ Karin Eastham                           Vice President, Finance and                         May 7, 1998
-----------------------------------         Administration, and Chief Financial Officer
Karin Eastham                               (Principal Financial and Accounting Officer)
                                   


/s/ Philippe O. Chambon, M.D., Ph.D.        Director                                            May 7, 1998
-----------------------------------
Philippe O. Chambon, M.D., Ph.D.


/s/ Arthur Reidel                           Director                                            May 7, 1998
-----------------------------------
Arthur Reidel


/s/ William Scott, Ph.D.                    Director                                            May 7, 1998
-----------------------------------
William Scott, Ph.D.
</TABLE>



                                      II-6.
<PAGE>   8
                       SECURITIES AND EXCHANGE COMMISSION

                                WASHINGTON, D.C.



                                    EXHIBITS

                                       TO

                                    FORM S-8

                                      UNDER

                             SECURITIES ACT OF 1933



                                 COMBICHEM, INC.



<PAGE>   9
                                  EXHIBIT INDEX




<TABLE>
<CAPTION>
    Number   Exhibit
    ------   -------
<S>          <C>
     4.1     Instruments Defining Rights of Stockholders.  Reference is made to Registrant's Registration
             Statement No. 000-23473 on Form 8-A and all exhibits thereto which are incorporated herein
             by reference pursuant to Item 3(b).
     5.1     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.
    24.1     Power of Attorney.  Reference is made to page II-5 of this Registration Statement.
*   99.1     1997 Stock Incentive Plan (Exhibit 10.44).
+   99.2     Form of Notice of Grant of Stock Option (Exhibit 10.48).
+   99.3     Form of Stock Option Agreement (Exhibit 10.49).
+   99.4     Form of Addendum to Stock Option Agreement (Involuntary Termination Following Corporate
             Transaction/Change in Control) (Exhibit 10.50).
+   99.5     Form of Addendum to Stock Option Agreement (Limited Stock Appreciation Right)
             (Exhibit 10.51)
+   99.6     Form of Stock Issuance Agreement (Exhibit 10.52).
+   99.7     Form of Addendum to Stock Issuance Agreement (Involuntary Termination Following
             Corporate Transaction/Change in Control) (Exhibit 10.53).
+   99.8     Form of Notice of Grant of Automatic Stock Option (Initial Grant) (Exhibit 10.54).
+   99.9     Form of Notice of Grant of Automatic Stock Option (Annual Grant) (Exhibit 10.55).
+   99.10    Form of Automatic Stock Option Agreement (Exhibit 10.56).
*   99.11    1997 Employee Stock Purchase Plan (Exhibit 10.45).
+   99.12    Form of Stock Purchase Agreement(Exhibit 10.57).
</TABLE>

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

*   These exhibits were previously filed as part of, and are hereby incorporated
    by reference to, the same numbered exhibit (except as otherwise noted) filed
    with the Registrant's Registration Statement on Form S-1 (Commission No.
    333-37981) filed on October 15, 1997.

+   These exhibits were previously filed as part of, and are hereby incorporated
    by reference to, the same numbered exhibit (except as otherwise noted) filed
    with the Registrant's Amendment No. 2 to Registration Statement on Form S-1
    (Commission No. 333-37981) filed on December 3, 1997.
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 23893}]
{"company-data": {"conformed-name": "COMBICHEM INC", "cik": "0001002276", "assigned-sic": "8731", "irs-number": "330617379", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-52063", "film-number": "98612838"}, "business-address": {"street1": "9050 CAMINO", "street2": "SUITE 200", "city": "SAN DIEGO", "state": "CA", "zip": "92121", "phone": "6195300484"}, "mail-address": {"street1": "9050 CAMINO SANTA FE", "city": "SAN DIEGO", "state": "CA", "zip": "92121"}}
1
      As filed with the Securities and Exchange Commission on May 7, 1998
                                           Registration No. 333-________________
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                                 COMBICHEM, INC.
               (Exact name of issuer as specified in its charter)

                DELAWARE                            33-0617379
      (State or other jurisdiction        (IRS Employer Identification No.)
     of incorporation or organization)

                9050 CAMINO SANTA FE, SAN DIEGO, CALIFORNIA 92121
               (Address of principal executive offices) (Zip Code)

                                 COMBICHEM, INC.
                          1997 STOCK INCENTIVE PLAN AND
                        1997 EMPLOYEE STOCK PURCHASE PLAN
                            (Full title of the plans)

                             DR. VICENTE ANIDO, JR.
                      PRESIDENT AND CHIEF EXECUTIVE OFFICER
                                 COMBICHEM, INC.
                              9050 CAMINO SANTA FE
                           SAN DIEGO, CALIFORNIA 92121
                     (Name and address of agent for service)
                                 (619) 530-0484
          (Telephone number, including area code, of agent for service)

                         CALCULATION OF REGISTRATION FEE
================================================================================================================
                                                                                  Proposed            Proposed
   Title of                                                                       Maximum              Maximum
  Securities                               Amount            Offering             Aggregate           Amount of
     to be                                  to be              Price              Offering          Registration
  Registered                            Registered(1)      per Share(2)             Price                Fee
  ----------                            -------------      ------------             -----                ---
1997 Stock Incentive Plan
Common Stock, par value               1,072,170 shares        $10.00           $10,721,700           $3,162.90
$0.001 per share

1997 Employee Stock Purchase Plan
Common Stock, par value
$0.001 per share                        150,000 shares        $10.00           $ 1,500,000           $  442.50
================================================================================================================
(1)  This Registration Statement shall also cover any additional shares of the
     Common Stock which become issuable under the Registrant's 1997 Stock
     Incentive Plan or 1997 Employee Stock Purchase Plan by reason of any stock
     dividend, stock split, recapitalization or other similar transaction
     effected without the receipt of consideration which results in an increase
     in the number of the outstanding shares of the Common Stock of CombiChem,
     Inc.

(2)  Estimated solely for the purpose of computing the amount of the
     registration fee.
2
                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.  Incorporation of Documents by Reference

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

         (a)      The Registrant's Prospectus filed April 7, 1998 with the
                  Registrant's Registration Statement No. 333-37981 on Form S-1,
                  as amended, under the Securities Act of 1933, as amended (the
                  "1933 Act"), in which there is set forth audited financial
                  statements for the Registrant's fiscal year ended December 31,
                  1997;

         (b)      The Registrant's Registration Statement on Form 8-A filed with
                  the SEC on May 4, 1998 pursuant to Section 12 of the
                  Securities Exchange Act of 1934, as amended (the "1934 Act"),
                  in which there is 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 and 15(d) of 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 deregisters 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

         Section 145 of the Delaware General Corporation Law permits
indemnification of officers and directors of the Company under certain
conditions and subject to certain limitations. Section 145 of the Delaware
General Corporation Law also provides that a corporation has the power to
purchase and maintain insurance on behalf of its officers and directors against
any liability asserted against such person and incurred by him or her in such
capacity, or arising out of his or her status as such, whether or not the
corporation would have the power to indemnify him or her against such liability
under the provisions of Section 145 of the Delaware General Corporation Law.

         Article VII, Section 1 of the Restated Bylaws of the Registrant
provides that the Registrant shall indemnify its directors and executive
officers to the fullest extent not prohibited by the Delaware General
Corporation Law. The rights to indemnify thereunder continue as to a person who
has ceased to be a director, officer, employee or agent and inure to the benefit
of the heirs, executors and administrators of the person. In addition, expenses
incurred by a director or executive officer in defending any civil, criminal,
administrative or investigative action, suit or proceeding by reason of the fact
that he or she is or was a director or officer of the Registrant (or was serving
at
3
the Registrant's request as a director or officer of another corporation) shall
be paid by the Registrant in advance of the final disposition of such action,
suit or proceeding upon receipt of an undertaking by or on behalf of such
director or officer to repay such amount if it shall ultimately be determined
that he or she is not entitled to be indemnified by the Registrant as authorized
by the relevant section of the Delaware General Corporation Law.

         As permitted by Section 102(b)(7) of the Delaware General Corporation
Law, Article V, Section (A) of the Registrant's Restated Certificate of
Incorporation provides that a director of the Registrant shall not be personally
liable for monetary damages for breach of fiduciary duty as a director, except
for liability (i) for any breach of the director's duty of loyalty to the
Registrant or its stockholders, (ii) for acts or omissions not in good faith or
acts or omissions that 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 any improper personal benefit.

         The Registrant has entered into indemnification agreements with each of
its directors and executive officers. Generally, the indemnification agreements
attempt to provide the maximum protection permitted by Delaware law as it may be
amended from time to time. Moreover, the indemnification agreements provide for
certain additional indemnification. Under such additional indemnification
provisions, however, an individual will not receive indemnification for
judgments, settlements or expenses if he or she is found liable to the
Registrant (except to the extent the court determines he or she is fairly and
reasonably entitled to indemnity for expenses), for settlements not approved by
the Registrant or for settlements and expenses if the settlement is not approved
by the court. The indemnification agreements provide for the Registrant to
advance to the individual any and all reasonable expenses (including legal fees
and expenses) incurred in investigating or defending any such action, suit or
proceeding. In order or receive an advance of expenses, the individual must
submit to the Registrant copies of invoices presented to him or her for such
expenses. Also, the individual must repay such advances upon a final judicial
decision that he or she is not entitled to indemnification.

         The Registrant has purchased directors' and officers' liability
insurance. The Registrant intends to enter into additional indemnification
agreements with each of its directors and executive officers to effectuate these
indemnity provisions.

Item 7.  Exemption from Registration Claimed

         Not Applicable.

                                      II-2.
4
Item 8.  Exhibits
Number   Exhibit
    ------   -------
4.1     Instruments Defining Rights of Stockholders.  Reference is made to Registrant's Registration
             Statement on Form 8-A, filed on May 4, 1998, and all exhibits thereto which are incorporated herein
             by reference pursuant to Item 3(b).
     5.1     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.
    24.1     Power of Attorney.  Reference is made to page II-5 of this Registration Statement.
*   99.1     1997 Stock Incentive Plan (Exhibit 10.44).
+   99.2     Form of Notice of Grant of Stock Option (Exhibit 10.48).
+   99.3     Form of Stock Option Agreement (Exhibit 10.49).
+   99.4     Form of Addendum to Stock Option Agreement (Involuntary Termination Following Corporate
             Transaction/Change in Control) (Exhibit 10.50).
+   99.5     Form of Addendum to Stock Option Agreement (Limited Stock Appreciation Right)
             (Exhibit 10.51)
+   99.6     Form of Stock Issuance Agreement (Exhibit 10.52).
+   99.7     Form of Addendum to Stock Issuance Agreement (Involuntary Termination Following
             Corporate Transaction/Change in Control) (Exhibit 10.53).
+   99.8     Form of Notice of Grant of Automatic Stock Option (Initial Grant) (Exhibit 10.54).
+   99.9     Form of Notice of Grant of Automatic Stock Option (Annual Grant) (Exhibit 10.55).
+   99.10    Form of Automatic Stock Option Agreement (Exhibit 10.56).
*   99.11    1997 Employee Stock Purchase Plan (Exhibit 10.45).
+   99.12    Form of Stock Purchase Agreement(Exhibit 10.57).
-----------------

*   These exhibits were previously filed as part of, and are hereby incorporated
    by reference to, the same numbered exhibit (except as otherwise noted) filed
    with the Registrant's Registration Statement on Form S-1 (Commission No.
    333-37981) initially filed on October 15, 1997, as amended.

+   These exhibits were previously filed as part of, and are hereby incorporated
    by reference to, the same numbered exhibit (except as otherwise noted) filed
    with the Registrant's Amendment No. 2 to Registration Statement on Form S-1
    (Commission No. 333-37981) initially filed on December 3, 1997, as amended.

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 paragraphs 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

                                      II-3.
5
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 1997 Stock Incentive Plan
and 1997 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 foregoing provisions, or otherwise, the Registrant
has been advised that, in the opinion of the SEC, 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-4.
6
                                   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 San Diego, State of California, on this 7th day
of May, 1998.

                                        COMBICHEM, INC.

                                        By: /s/ Vicente Anido, Jr., Ph.D.
                                           --------------------------------
                                           Vicente Anido, Jr., Ph.D.
                                           President, Chief Executive Officer 
                                           and Director (Principal Executive 
                                           Officer)

                                POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS:

         That the undersigned officers and directors of CombiChem, Inc., a
Delaware corporation, do hereby constitute and appoint Vicente Anido, Jr., Ph.D.
and Karin Eastham, and each of them, with full power of substitution and
resubstitution, 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 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 the undersigned
hereby ratifies and confirms that said attorneys and agents, each acting alone,
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/ Pierre R. Lamond                        Chairman of the Board and Director          May 7, 1998
------------------------------------
Pierre R. Lamond
II-5.
7
Signature                                   Title                                               Date
---------                                   -----                                               ----
/s/ Vicente Anido, Jr., Ph.D.               President, Chief Executive Officer                  May 7, 1998
-----------------------------------         and Director (Principal Executive Officer)
Vicente Anido, Jr., Ph.D.          

/s/ Peter L. Myers, Ph.D.                   Vice President, Chief Scientific Officer,           May 7, 1998
-----------------------------------         Chief Operating Officer and Director
Peter L. Myers, Ph.D.              

/s/ Karin Eastham                           Vice President, Finance and                         May 7, 1998
-----------------------------------         Administration, and Chief Financial Officer
Karin Eastham                               (Principal Financial and Accounting Officer)
                                   

/s/ Philippe O. Chambon, M.D., Ph.D.        Director                                            May 7, 1998
-----------------------------------
Philippe O. Chambon, M.D., Ph.D.

/s/ Arthur Reidel                           Director                                            May 7, 1998
-----------------------------------
Arthur Reidel

/s/ William Scott, Ph.D.                    Director                                            May 7, 1998
-----------------------------------
William Scott, Ph.D.
II-6.
8
                       SECURITIES AND EXCHANGE COMMISSION

                                WASHINGTON, D.C.

                                    EXHIBITS

                                       TO

                                    FORM S-8

                                      UNDER

                             SECURITIES ACT OF 1933

                                 COMBICHEM, INC.
9
                                  EXHIBIT INDEX
Number   Exhibit
    ------   -------
4.1     Instruments Defining Rights of Stockholders.  Reference is made to Registrant's Registration
             Statement No. 000-23473 on Form 8-A and all exhibits thereto which are incorporated herein
             by reference pursuant to Item 3(b).
     5.1     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.
    24.1     Power of Attorney.  Reference is made to page II-5 of this Registration Statement.
*   99.1     1997 Stock Incentive Plan (Exhibit 10.44).
+   99.2     Form of Notice of Grant of Stock Option (Exhibit 10.48).
+   99.3     Form of Stock Option Agreement (Exhibit 10.49).
+   99.4     Form of Addendum to Stock Option Agreement (Involuntary Termination Following Corporate
             Transaction/Change in Control) (Exhibit 10.50).
+   99.5     Form of Addendum to Stock Option Agreement (Limited Stock Appreciation Right)
             (Exhibit 10.51)
+   99.6     Form of Stock Issuance Agreement (Exhibit 10.52).
+   99.7     Form of Addendum to Stock Issuance Agreement (Involuntary Termination Following
             Corporate Transaction/Change in Control) (Exhibit 10.53).
+   99.8     Form of Notice of Grant of Automatic Stock Option (Initial Grant) (Exhibit 10.54).
+   99.9     Form of Notice of Grant of Automatic Stock Option (Annual Grant) (Exhibit 10.55).
+   99.10    Form of Automatic Stock Option Agreement (Exhibit 10.56).
*   99.11    1997 Employee Stock Purchase Plan (Exhibit 10.45).
+   99.12    Form of Stock Purchase Agreement(Exhibit 10.57).
-----------------

*   These exhibits were previously filed as part of, and are hereby incorporated
    by reference to, the same numbered exhibit (except as otherwise noted) filed
    with the Registrant's Registration Statement on Form S-1 (Commission No.
    333-37981) filed on October 15, 1997.

+   These exhibits were previously filed as part of, and are hereby incorporated
    by reference to, the same numbered exhibit (except as otherwise noted) filed
    with the Registrant's Amendment No. 2 to Registration Statement on Form S-1
    (Commission No. 333-37981) filed on December 3, 1997.