<PAGE>   1
      AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON APRIL 5, 2000

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

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

                              PHARMACIA CORPORATION
               (Exact Name of Company as Specified in its Charter)

<TABLE>
<S>                                                   <C>
                DELAWARE                                           43-0420020
    (State or Other Jurisdiction of                   (I.R.S. Employer Identification No.)
     Incorporation or Organization)

          100 ROUTE 206 NORTH                                        07977
          PEAPACK, NEW JERSEY                                      (Zip Code)
(Address of principal executive offices)
</TABLE>

                PHARMACIA & UPJOHN, INC. LONG-TERM INCENTIVE PLAN
                PHARMACIA & UPJOHN, INC. EQUITY COMPENSATION PLAN
    PHARMACIA & UPJOHN, INC. DIRECTORS EQUITY COMPENSATION AND DEFERRAL PLAN
                            (Full title of the plans)

                              DON W. SCHMITZ, ESQ.
        VICE PRESIDENT, ASSOCIATE GENERAL COUNSEL AND CORPORATE SECRETARY
                              PHARMACIA CORPORATION
                               100 ROUTE 206 NORTH
                            PEAPACK, NEW JERSEY 07977
                     (Name and address of agent for service)

                                 (908) 901-8000
          (Telephone number, including area code, of agent for service)

                         CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
--------------------------------------------- -------------------- ---------------------- ---------------------- -------------------
                                                                     PROPOSED MAXIMUM       PROPOSED MAXIMUM         AMOUNT OF
              TITLE OF SECURITIES                AMOUNT TO BE       OFFERING PRICE PER     AGGREGATE OFFERING     REGISTRATION FEE
                TO BE REGISTERED                REGISTERED (1)           SHARE (2)              PRICE (2)               (2)
--------------------------------------------- -------------------- ---------------------- ---------------------- -------------------
<S>                                           <C>                  <C>                    <C>                    <C>
Common Stock, par value $2.00 per share, and
associated preferred stock purchase
rights.......................................    38,962,980            $46.375               $1,806,908,197.5         $477,024
============================================= ==================== ====================== ====================== ===================
</TABLE>

 (1) This Registration Statement covers shares of Common Stock of Pharmacia
     Corporation and associated preferred stock purchase rights which may be
     offered or sold pursuant to the Pharmacia & Upjohn, Inc. Long Term
     Incentive Plan, Pharmacia & Upjohn, Inc. Equity Compensation Plan and
     Pharmacia & Upjohn, Inc. Directors Equity Compensation and Deferral Plan.
     35,224,000 shares are being registered pursuant to the Pharmacia & Upjohn,
     Inc. Long Term Incentive Plan, 3,706,850 shares are being registered
     pursuant to the Pharmacia & Upjohn, Inc. Equity Compensation Plan and
     32,130 shares are being registered pursuant to the Pharmacia & Upjohn, Inc.
     Directors Equity Compensation and Deferral Plan. Pursuant to Rule 416 under
     the Securities Act of 1933, as amended (the "Securities Act"), this
     Registration Statement also covers such additional shares as may
     hereinafter be offered or issued to prevent dilution resulting from stock
     splits, stock dividends, recapitalizations or certain other capital
     adjustments.

(2)  Estimated pursuant to Paragraphs (c) and (h) of Rule 457 under the
     Securities Act, solely for the purpose of calculating the registration fee,
     based upon the average of the high and low sales prices of shares of
     Monsanto Company Common Stock on March 29, 2000, as reported on the New
     York Stock Exchange, Inc.
<PAGE>   2
                                     PART I
              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS


ITEM 1.           PLAN INFORMATION

         All information required by Part I to be contained in the prospectus is
omitted from this Registration Statement in accordance with Rule 424 and Rule
428 under the Securities Act.



ITEM 2.           REGISTRANT INFORMATION AND EMPLOYEE PLAN ANNUAL INFORMATION

         Any documents which Pharmacia Corporation (formerly Monsanto Company)
(the "Company") incorporated by reference in Item 3 of Part II of this Form S-8
Registration Statement (the "Registration Statement") are incorporated by
reference in the Section 10(a) prospectus and are available without charge, upon
written or oral request, by contacting the Company at 100 Route 206, Peapack,
New Jersey 07977 (908) 901-8000. All other information required by Part I to be
contained in the Section 10(a) prospectus is omitted from this Registration
Statement in accordance with Rule 424 and Rule 428 under the Securities Act and
the "Note" to Part I of this Form S-8.


                                      I-1
<PAGE>   3
                                     PART II
               INFORMATION REQUIRED IN THE REGISTRATION STATEMENTS

ITEM 3.           INCORPORATION OF DOCUMENTS BY REFERENCE.

         The following documents filed with the United States Securities and
Exchange Commission (the "Commission") by the Company (File No. 1-2516) pursuant
to the Securities Exchange Act of 1934, as amended (the "Exchange Act"), are
hereby incorporated by reference in this Registration Statement and made a part
hereof:

1.   The Company's Annual Report on Form 10-K for the year ended December 31,
     1999, as filed on March 20, 2000;

2.   The Company's amended Annual Report on Form 10-K/A for the year ended
     December 31, 1998, as filed on January 21, 2000;

3.   The Company's amended Quarterly Reports on Form 10-Q/A for the quarters
     ended March 31, 1999, June 30, 1999 and September 30,1999, as filed on
     January 21, 2000;

4.   The Company's Current Reports on Form 8-K, as filed on January 11, 2000,
     January 25, 2000 and February 11, 2000;

5.   The Company's amended Current Report on Form 8-K/A, as filed on January 25,
     2000 and February 11, 2000;

6.   The description of the Company's common stock, par value $2.00 per share,
     and the description of associated Preferred Stock Purchase Rights contained
     in registration statements filed under the Exchange Act, including any
     amendment or report filed for the purpose of updating such description.


         All documents and reports filed by the Company pursuant to Section
13(a), 13(c), 14 or 15(d) of the Exchange 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 herein and to be a part hereof from the date of filing
of such documents or reports. 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 other subsequently filed document which
also is or is deemed to be incorporated by reference herein modifies or
supersedes such statement. Any such statement so modified shall not be deemed to
constitute a part of the Registration Statement except as so modified and any
statement so superseded shall not be deemed to constitute a part of this
Registration Statement.

Independent Accountants

         The financial statements of the Company incorporated in this
Registration Statement by reference from the Company's Annual Report on
Form 10-K for the year ended December 31, 1999 have been audited by Deloitte &
Touche LLP, independent auditors, as stated in their report, which is
incorporated herein by reference, and have been so incorporated in reliance
upon the report of such firm given upon their authority as experts in
accounting and auditing.


                                      II-1
<PAGE>   4
         The financial statements of Pharmacia & Upjohn, Inc. incorporated in
this Registration Statement by reference to the Current Report on Form 8-K of
Monsanto Company filed on January 25, 2000, have been so incorporated in
reliance on the report of PricewaterhouseCoopers LLP, independent accountants,
given on the authority of said firm as experts in auditing and accounting.

         The financial statements of DEKALB Genetics Corporation incorporated in
this Registration Statement by reference to the Current Report on Form 8-K/A of
Monsanto Company filed on February 8, 1999 and January 25, 2000, have been so
incorporated in reliance on the report of Arthur Andersen LLP, independent
public accountants, given on the authority of said firm as experts in auditing
and accounting.

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 authorizes a court
to award, or a corporation's board of directors to grant, indemnity to directors
and officers in terms sufficiently broad to permit such indemnification under
certain circumstances for liabilities (including reimbursement for expenses
incurred) arising under the Securities Act. The Company's Certificate of
Incorporation and By-laws provide for indemnification of its directors,
officers, employees and other agents to the maximum extent permitted by the
Delaware General Corporation Law. In addition, the Company has entered into
Indemnification Agreements with its executive officers and directors. The
Company has also purchased and maintained insurance for its officers, directors,
employees or agents against liabilities which an officer, a director, an
employee or an agent may incur in his capacity as such.

ITEM 7.           EXEMPTION FROM REGISTRATION CLAIMED.

                  Not Applicable

ITEM 8.           EXHIBITS.

EXHIBIT NUMBERS                    EXHIBIT
---------------                    -------

     4.1          Restated Certificate of Incorporation of Pharmacia
                  Corporation.

     4.2          Certificate of Amendment of Pharmacia Corporation Restated
                  Certificate of Incorporation.

     4.3          Amended and Restated Bylaws of Pharmacia Corporation.

     4.4          Rights Agreement, dated as of December 19, 1999 between the
                  Company and EquiServe Trust Company N.A., First Chicago Trust
                  Company as successor to The First National Bank of Boston
                  (incorporated herein by reference to Form 8-A filed on
                  December 30, 1999).

     5.1          Opinion of Sullivan & Cromwell.


                                      II-2
<PAGE>   5
     23.1         Consent of Deloitte & Touche LLP.

     23.2         Consent of PricewaterhouseCoopers LLP.

     23.3         Consent of Arthur Andersen LLP.

     23.4         Consent of Sullivan & Cromwell (included as part of Exhibit
                  5.1).



ITEM 9.           UNDERTAKINGS.

         The undersigned 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 Securities Act;

              (ii)  To reflect in the prospectus any facts or events arising
                    after the effective date of the 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 the Registration
                    Statement.

              (iii) To include any material information with respect to the plan
                    of distribution not previously disclosed in the Registration
                    Statement or any material change to such information in the
                    Registration Statement;

              provided, however, that subparagraphs (a)(1)(i) and (a)(1)(ii) of
              this section do not apply if the information required to be
              included in a post-effective amendment by those subparagraphs is
              contained in periodic reports filed with or furnished to the
              Commission by the Company pursuant to Section 13 or Section 15(d)
              of the Exchange Act that are incorporated by reference in the
              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 a post-effective amendment
              any of the securities being registered that remain unsold at the
              termination of the offering.


                                      II-3
<PAGE>   6
         The undersigned company hereby undertakes that, for purposes of
determining any liability under the Securities Act, each filing of the Company's
annual report pursuant to Section 13(a) or 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
Company pursuant to the foregoing provisions, or otherwise, the Company has been
advised that in the opinion of the 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 Company of expenses incurred or paid
by a director, officer or controlling person of the Company 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
Company 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.


                                      II-4
<PAGE>   7
                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, the Company
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 Peapack, State of New Jersey on April 3, 2000.

                                        PHARMACIA CORPORATION


                                        By:       /s/ Fred Hassan
                                        Name:     Fred Hassan
                                        Title:    Chief Executive Officer and
                                                  Director

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

<TABLE>
<CAPTION>
NAME                                      TITLE                                  DATE
----                                      -----                                  ----
<S>                                       <C>                                    <C>
/s/ Fred Hassan                           Chief Executive Office and             April 3, 2000
-----------------------------------       Director (Principal Executive
Fred Hassan                               Officer)


/s/ Christopher Coughlin                  Executive Vice President and           April 3, 2000
-----------------------------------       Chief Financial Officer
Christopher Coughlin                      (Principal Financial and Accounting
                                          Officer)


/s/ M. Kathryn Eickhoff
-----------------------------------       Director                               April 3, 2000
M. Kathryn Eickhoff


/s/ Michael Kantor
-----------------------------------       Director                               April 3, 2000
Michael Kantor


/s/ Gwendolyn S. King
-----------------------------------       Director                               April 3, 2000
Gwendolyn S. King


/s/ Philip Leder
-----------------------------------       Director                               April 3, 2000
Philip Leder
</TABLE>


                                      II-5
<PAGE>   8
<TABLE>
<S>                                       <C>                                    <C>
/s/ Olof G. Lund
-----------------------------------       Director                               April 3, 2000
Olof G. Lund


/s/ C. Steven McMillan
-----------------------------------       Director                               April 3, 2000
C. Steven McMillan



/s/ Jacobus F.M. Peters
-----------------------------------       Director                               April 3, 2000
Jacobus F.M. Peters


/s/ John S. Reed
-----------------------------------       Director                               April 3, 2000
John S. Reed


/s/ Ulla B. Reinius
-----------------------------------       Director                               April 3, 2000
Ulla B. Reinius


/s/ John E. Robson
-----------------------------------       Director                               April 3, 2000
John E. Robson


/s/ Robert B. Shapiro
-----------------------------------       Chairman of the Board of               April 3, 2000
Robert B. Shapiro                         Directors
</TABLE>


                                      II-6
<PAGE>   9
                                INDEX TO EXHIBITS


EXHIBIT NUMBERS                    EXHIBIT
---------------                    -------

     4.1           Restated Certificate of Incorporation of Pharmacia
                   Corporation.

     4.2           Certificate of Amendment of Pharmacia Corporation Restated
                   Certificate of Incorporation.

     4.3           Amended and Restated Bylaws of Pharmacia Corporation.

     4.4           Rights Agreement, dated as of December 19, 1999 between the
                   Company and EquiServe Trust Company N.A., First Chicago Trust
                   Company as successor to The First National Bank of Boston
                   (incorporated herein by reference to Form 8-A filed on
                   December 30, 1999).

     5.1           Opinion of Sullivan & Cromwell.

     23.1          Consent of Deloitte & Touche LLP.

     23.2          Consent of PricewaterhouseCoopers LLP.

     23.3          Consent of Arthur Andersen LLP.

     23.4          Consent of Sullivan & Cromwell (included as part of Exhibit
                   5.1).
[{"type": "S-8", "sequence": "1", "description": "PHARMACIA CORPORATION", "secsgml_size_bytes": 20175}]
{"company-data": {"conformed-name": "PHARMACIA CORP /DE/", "cik": "0000067686", "assigned-sic": "2800", "irs-number": "430420020", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-34112", "film-number": "594374"}, "business-address": {"street1": "800 N LINDBERGH BLVD", "city": "ST LOUIS", "state": "MO", "zip": "63167", "phone": "3146941000"}, "mail-address": {"street1": "800 NORTH LINDBERGH BLVD", "city": "ST LOUIS", "state": "MO", "zip": "63167"}, "former-company": [{"former-conformed-name": "MONSANTO CO", "date-changed": "19920703"}, {"former-conformed-name": "MONSANTO CHEMICAL CO", "date-changed": "19711003"}]}
1
      AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON APRIL 5, 2000

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

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

                              PHARMACIA CORPORATION
               (Exact Name of Company as Specified in its Charter)
DELAWARE                                           43-0420020
    (State or Other Jurisdiction of                   (I.R.S. Employer Identification No.)
     Incorporation or Organization)

          100 ROUTE 206 NORTH                                        07977
          PEAPACK, NEW JERSEY                                      (Zip Code)
(Address of principal executive offices)
PHARMACIA & UPJOHN, INC. LONG-TERM INCENTIVE PLAN
                PHARMACIA & UPJOHN, INC. EQUITY COMPENSATION PLAN
    PHARMACIA & UPJOHN, INC. DIRECTORS EQUITY COMPENSATION AND DEFERRAL PLAN
                            (Full title of the plans)

                              DON W. SCHMITZ, ESQ.
        VICE PRESIDENT, ASSOCIATE GENERAL COUNSEL AND CORPORATE SECRETARY
                              PHARMACIA CORPORATION
                               100 ROUTE 206 NORTH
                            PEAPACK, NEW JERSEY 07977
                     (Name and address of agent for service)

                                 (908) 901-8000
          (Telephone number, including area code, of agent for service)

                         CALCULATION OF REGISTRATION FEE
--------------------------------------------- -------------------- ---------------------- ---------------------- -------------------
                                                                     PROPOSED MAXIMUM       PROPOSED MAXIMUM         AMOUNT OF
              TITLE OF SECURITIES                AMOUNT TO BE       OFFERING PRICE PER     AGGREGATE OFFERING     REGISTRATION FEE
                TO BE REGISTERED                REGISTERED (1)           SHARE (2)              PRICE (2)               (2)
--------------------------------------------- -------------------- ---------------------- ---------------------- -------------------
Common Stock, par value $2.00 per share, and
associated preferred stock purchase
rights.......................................    38,962,980            $46.375               $1,806,908,197.5         $477,024
============================================= ==================== ====================== ====================== ===================
(1) This Registration Statement covers shares of Common Stock of Pharmacia
     Corporation and associated preferred stock purchase rights which may be
     offered or sold pursuant to the Pharmacia & Upjohn, Inc. Long Term
     Incentive Plan, Pharmacia & Upjohn, Inc. Equity Compensation Plan and
     Pharmacia & Upjohn, Inc. Directors Equity Compensation and Deferral Plan.
     35,224,000 shares are being registered pursuant to the Pharmacia & Upjohn,
     Inc. Long Term Incentive Plan, 3,706,850 shares are being registered
     pursuant to the Pharmacia & Upjohn, Inc. Equity Compensation Plan and
     32,130 shares are being registered pursuant to the Pharmacia & Upjohn, Inc.
     Directors Equity Compensation and Deferral Plan. Pursuant to Rule 416 under
     the Securities Act of 1933, as amended (the "Securities Act"), this
     Registration Statement also covers such additional shares as may
     hereinafter be offered or issued to prevent dilution resulting from stock
     splits, stock dividends, recapitalizations or certain other capital
     adjustments.

(2)  Estimated pursuant to Paragraphs (c) and (h) of Rule 457 under the
     Securities Act, solely for the purpose of calculating the registration fee,
     based upon the average of the high and low sales prices of shares of
     Monsanto Company Common Stock on March 29, 2000, as reported on the New
     York Stock Exchange, Inc.
2
                                     PART I
              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

ITEM 1.           PLAN INFORMATION

         All information required by Part I to be contained in the prospectus is
omitted from this Registration Statement in accordance with Rule 424 and Rule
428 under the Securities Act.

ITEM 2.           REGISTRANT INFORMATION AND EMPLOYEE PLAN ANNUAL INFORMATION

         Any documents which Pharmacia Corporation (formerly Monsanto Company)
(the "Company") incorporated by reference in Item 3 of Part II of this Form S-8
Registration Statement (the "Registration Statement") are incorporated by
reference in the Section 10(a) prospectus and are available without charge, upon
written or oral request, by contacting the Company at 100 Route 206, Peapack,
New Jersey 07977 (908) 901-8000. All other information required by Part I to be
contained in the Section 10(a) prospectus is omitted from this Registration
Statement in accordance with Rule 424 and Rule 428 under the Securities Act and
the "Note" to Part I of this Form S-8.

                                      I-1
3
                                     PART II
               INFORMATION REQUIRED IN THE REGISTRATION STATEMENTS

ITEM 3.           INCORPORATION OF DOCUMENTS BY REFERENCE.

         The following documents filed with the United States Securities and
Exchange Commission (the "Commission") by the Company (File No. 1-2516) pursuant
to the Securities Exchange Act of 1934, as amended (the "Exchange Act"), are
hereby incorporated by reference in this Registration Statement and made a part
hereof:

1.   The Company's Annual Report on Form 10-K for the year ended December 31,
     1999, as filed on March 20, 2000;

2.   The Company's amended Annual Report on Form 10-K/A for the year ended
     December 31, 1998, as filed on January 21, 2000;

3.   The Company's amended Quarterly Reports on Form 10-Q/A for the quarters
     ended March 31, 1999, June 30, 1999 and September 30,1999, as filed on
     January 21, 2000;

4.   The Company's Current Reports on Form 8-K, as filed on January 11, 2000,
     January 25, 2000 and February 11, 2000;

5.   The Company's amended Current Report on Form 8-K/A, as filed on January 25,
     2000 and February 11, 2000;

6.   The description of the Company's common stock, par value $2.00 per share,
     and the description of associated Preferred Stock Purchase Rights contained
     in registration statements filed under the Exchange Act, including any
     amendment or report filed for the purpose of updating such description.

         All documents and reports filed by the Company pursuant to Section
13(a), 13(c), 14 or 15(d) of the Exchange 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 herein and to be a part hereof from the date of filing
of such documents or reports. 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 other subsequently filed document which
also is or is deemed to be incorporated by reference herein modifies or
supersedes such statement. Any such statement so modified shall not be deemed to
constitute a part of the Registration Statement except as so modified and any
statement so superseded shall not be deemed to constitute a part of this
Registration Statement.

Independent Accountants

         The financial statements of the Company incorporated in this
Registration Statement by reference from the Company's Annual Report on
Form 10-K for the year ended December 31, 1999 have been audited by Deloitte &
Touche LLP, independent auditors, as stated in their report, which is
incorporated herein by reference, and have been so incorporated in reliance
upon the report of such firm given upon their authority as experts in
accounting and auditing.

                                      II-1
4
         The financial statements of Pharmacia & Upjohn, Inc. incorporated in
this Registration Statement by reference to the Current Report on Form 8-K of
Monsanto Company filed on January 25, 2000, have been so incorporated in
reliance on the report of PricewaterhouseCoopers LLP, independent accountants,
given on the authority of said firm as experts in auditing and accounting.

         The financial statements of DEKALB Genetics Corporation incorporated in
this Registration Statement by reference to the Current Report on Form 8-K/A of
Monsanto Company filed on February 8, 1999 and January 25, 2000, have been so
incorporated in reliance on the report of Arthur Andersen LLP, independent
public accountants, given on the authority of said firm as experts in auditing
and accounting.

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 authorizes a court
to award, or a corporation's board of directors to grant, indemnity to directors
and officers in terms sufficiently broad to permit such indemnification under
certain circumstances for liabilities (including reimbursement for expenses
incurred) arising under the Securities Act. The Company's Certificate of
Incorporation and By-laws provide for indemnification of its directors,
officers, employees and other agents to the maximum extent permitted by the
Delaware General Corporation Law. In addition, the Company has entered into
Indemnification Agreements with its executive officers and directors. The
Company has also purchased and maintained insurance for its officers, directors,
employees or agents against liabilities which an officer, a director, an
employee or an agent may incur in his capacity as such.

ITEM 7.           EXEMPTION FROM REGISTRATION CLAIMED.

                  Not Applicable

ITEM 8.           EXHIBITS.

EXHIBIT NUMBERS                    EXHIBIT
---------------                    -------

     4.1          Restated Certificate of Incorporation of Pharmacia
                  Corporation.

     4.2          Certificate of Amendment of Pharmacia Corporation Restated
                  Certificate of Incorporation.

     4.3          Amended and Restated Bylaws of Pharmacia Corporation.

     4.4          Rights Agreement, dated as of December 19, 1999 between the
                  Company and EquiServe Trust Company N.A., First Chicago Trust
                  Company as successor to The First National Bank of Boston
                  (incorporated herein by reference to Form 8-A filed on
                  December 30, 1999).

     5.1          Opinion of Sullivan & Cromwell.

                                      II-2
5
     23.1         Consent of Deloitte & Touche LLP.

     23.2         Consent of PricewaterhouseCoopers LLP.

     23.3         Consent of Arthur Andersen LLP.

     23.4         Consent of Sullivan & Cromwell (included as part of Exhibit
                  5.1).

ITEM 9.           UNDERTAKINGS.

         The undersigned 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 Securities Act;

              (ii)  To reflect in the prospectus any facts or events arising
                    after the effective date of the 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 the Registration
                    Statement.

              (iii) To include any material information with respect to the plan
                    of distribution not previously disclosed in the Registration
                    Statement or any material change to such information in the
                    Registration Statement;

              provided, however, that subparagraphs (a)(1)(i) and (a)(1)(ii) of
              this section do not apply if the information required to be
              included in a post-effective amendment by those subparagraphs is
              contained in periodic reports filed with or furnished to the
              Commission by the Company pursuant to Section 13 or Section 15(d)
              of the Exchange Act that are incorporated by reference in the
              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 a post-effective amendment
              any of the securities being registered that remain unsold at the
              termination of the offering.

                                      II-3
6
         The undersigned company hereby undertakes that, for purposes of
determining any liability under the Securities Act, each filing of the Company's
annual report pursuant to Section 13(a) or 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
Company pursuant to the foregoing provisions, or otherwise, the Company has been
advised that in the opinion of the 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 Company of expenses incurred or paid
by a director, officer or controlling person of the Company 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
Company 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.

                                      II-4
7
                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, the Company
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 Peapack, State of New Jersey on April 3, 2000.

                                        PHARMACIA CORPORATION

                                        By:       /s/ Fred Hassan
                                        Name:     Fred Hassan
                                        Title:    Chief Executive Officer and
                                                  Director

         Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed below by the following persons in the
capacities and on the dates indicated.
NAME                                      TITLE                                  DATE
----                                      -----                                  ----
/s/ Fred Hassan                           Chief Executive Office and             April 3, 2000
-----------------------------------       Director (Principal Executive
Fred Hassan                               Officer)

/s/ Christopher Coughlin                  Executive Vice President and           April 3, 2000
-----------------------------------       Chief Financial Officer
Christopher Coughlin                      (Principal Financial and Accounting
                                          Officer)

/s/ M. Kathryn Eickhoff
-----------------------------------       Director                               April 3, 2000
M. Kathryn Eickhoff

/s/ Michael Kantor
-----------------------------------       Director                               April 3, 2000
Michael Kantor

/s/ Gwendolyn S. King
-----------------------------------       Director                               April 3, 2000
Gwendolyn S. King

/s/ Philip Leder
-----------------------------------       Director                               April 3, 2000
Philip Leder
II-5
8
/s/ Olof G. Lund
-----------------------------------       Director                               April 3, 2000
Olof G. Lund

/s/ C. Steven McMillan
-----------------------------------       Director                               April 3, 2000
C. Steven McMillan

/s/ Jacobus F.M. Peters
-----------------------------------       Director                               April 3, 2000
Jacobus F.M. Peters

/s/ John S. Reed
-----------------------------------       Director                               April 3, 2000
John S. Reed

/s/ Ulla B. Reinius
-----------------------------------       Director                               April 3, 2000
Ulla B. Reinius

/s/ John E. Robson
-----------------------------------       Director                               April 3, 2000
John E. Robson

/s/ Robert B. Shapiro
-----------------------------------       Chairman of the Board of               April 3, 2000
Robert B. Shapiro                         Directors
II-6
9
                                INDEX TO EXHIBITS

EXHIBIT NUMBERS                    EXHIBIT
---------------                    -------

     4.1           Restated Certificate of Incorporation of Pharmacia
                   Corporation.

     4.2           Certificate of Amendment of Pharmacia Corporation Restated
                   Certificate of Incorporation.

     4.3           Amended and Restated Bylaws of Pharmacia Corporation.

     4.4           Rights Agreement, dated as of December 19, 1999 between the
                   Company and EquiServe Trust Company N.A., First Chicago Trust
                   Company as successor to The First National Bank of Boston
                   (incorporated herein by reference to Form 8-A filed on
                   December 30, 1999).

     5.1           Opinion of Sullivan & Cromwell.

     23.1          Consent of Deloitte & Touche LLP.

     23.2          Consent of PricewaterhouseCoopers LLP.

     23.3          Consent of Arthur Andersen LLP.

     23.4          Consent of Sullivan & Cromwell (included as part of Exhibit
                   5.1).