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                SECURITIES AND EXCHANGE COMMISSION
                     WASHINGTON, D.C.  20549
                     -----------------------

                           FORM 10-K/A
                     -----------------------

      AMENDMENT #1 TO ANNUAL REPORT PURSUANT TO SECTION 13 OF
                THE SECURITIES EXCHANGE ACT OF 1934

FOR THE FISCAL YEAR                    COMMISSION FILE NO. 1-11792
   ENDED DECEMBER 31, 1996

                   MERCANTILE BANCORPORATION INC.
        (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)

       MISSOURI                             43-0951744
(STATE OF INCORPORATION)                   (IRS EMPLOYER
                                         IDENTIFICATION NO.)


             P.O. BOX 524                       63166-0524
        ST. LOUIS, MISSOURI                     (ZIP CODE)
(ADDRESS OF PRINCIPAL EXECUTIVE OFFICES)

   REGISTRANT'S TELEPHONE NUMBER, INCLUDING AREA CODE:  314-425-2525

SECURITIES REGISTERED PURSUANT           NAME OF EXCHANGE ON WHICH REGISTERED:
      TO SECTION 12(b) OF THE ACT:

(1) COMMON STOCK ($0.01 PAR VALUE)        (1) NEW YORK STOCK EXCHANGE
(2) PREFERRED STOCK PURCHASE RIGHTS       (2) NEW YORK STOCK EXCHANGE

SECURITIES REGISTERED PURSUANT TO SECTION 12(g) OF THE ACT:   NONE

    INDICATE BY CHECK MARK WHETHER THE REGISTRANT (1) HAS FILED
ALL REPORTS REQUIRED TO BE FILED BY SECTION 13 OF THE SECURITIES
EXCHANGE ACT OF 1934 DURING THE PRECEDING 12 MONTHS, AND (2) HAS
BEEN SUBJECT TO SUCH FILING REQUIREMENTS FOR THE PAST 90 DAYS.
YES    X       NO
     -----       -----

    INDICATE BY CHECK MARK IF DISCLOSURE OF DELINQUENT FILERS
PURSUANT TO ITEM 405 OF REGULATION S-K IS NOT CONTAINED HEREIN,
AND WILL NOT BE CONTAINED, TO THE BEST OF REGISTRANT'S KNOWLEDGE,
IN DEFINITIVE PROXY OR INFORMATION STATEMENTS INCORPORATED BY
REFERENCE IN PART III OF THIS FORM 10-K.  [X]

 STATE THE AGGREGATE MARKET VALUE OF THE VOTING STOCK HELD BY
   NON-AFFILIATES OF THE REGISTRANT AS OF JANUARY 31, 1997:

        COMMON STOCK, $5.00 PAR VALUE, $2,566,265,226

  INDICATE THE NUMBER OF SHARES OUTSTANDING OF EACH OF THE
REGISTRANT'S CLASSES OF COMMON STOCK, AS OF JANUARY 31, 1997:

 COMMON STOCK $5.00 PAR VALUE, 60,757,050 SHARES OUTSTANDING

              DOCUMENT INCORPORATED BY REFERENCE

AS PROVIDED HEREIN, PORTIONS OF THE DOCUMENT BELOW ARE INCORPORATED BY
REFERENCE:
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<CAPTION>
             DOCUMENT                                                       PART--FORM 10-K
             --------                                                       ---------------
<S>                                                                               <C>
REGISTRANT'S PROXY STATEMENT FOR THE 1997 ANNUAL MEETING OF SHAREHOLDERS.         III
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The "Exhibit Index" as previously filed with the Form 10-K is hereby amended
by inserting the following entries:


   No. 23-1    Consent of KPMG Peat Marwick LLP (relating to report dated
               June 20, 1997, Mercantile Bancorporation Inc. Horizon
               Investment and Savings Plan and Trust Financial Statements.)

   No. 99      Report of the Independent Auditors KPMG Peat Marwick LLP dated
               June 20, 1997; Statements of Assets Available for Plan
               Benefits of Mercantile Bancorporation Inc. Horizon Investment
               and Savings Plan and Trust as of December 31, 1996 and 1995;
               Statements of Changes in Assets Available For Plan Benefits
               for the years then ended; and the Notes and Schedules thereto.

The Exhibit Index, as amended, follows, and new Exhibits 23-1 and 99 are filed
herewith.



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<TABLE>
                               EXHIBIT INDEX
<CAPTION>

Exhibit No.                           Description
----------                            -----------
<C>            <S>
No. 3-1        Restated Articles of Incorporation of the Registrant, as
               amended and currently in effect, filed as Exhibit 3(i) to
               Registrant's Quarterly Report on Form 10-Q for the quarter
               ended June 30, 1994, are incorporated herein by reference.

No. 3-2        By-Laws of the Registrant, as amended and currently in effect,
               filed as Exhibit 3.2 to Amendment No. 2 to Registrant's
               Registration Statement No. 333-17757, are incorporated herein
               by reference.

No. 4-1        Form of Indenture Regarding Subordinated Securities between the
               Registrant and The First National Bank of Chicago as Trustee,
               filed on March 31, 1992, as Exhibit 4.1 to Registrant's Report
               on Form 8-K dated September 24, 1992, is incorporated herein by
               reference.

No. 4-2        Form of Indenture Regarding Floating Rate Junior Subordinated
               Definable Interest Debentures due 2027 between the Registrant
               and the Chase Manhattan Bank, as Trustee.

No. 4-3        Form of First Supplemental Indenture Regarding Floating Rate
               Junior Subordinated Definable Interest Debentures Due 2027
               between the Registrant and the Chase Manhattan Bank, as
               Trustee.

No. 4-4        Rights Agreement dated as of May 23, 1988, between Registrant
               and Mercantile Bank National Association, as Rights Agent
               (including as exhibits thereto the form of Certificate of
               Designation, Preferences and Rights of Series A Junior
               Participating Preferred Stock and the form of Rights
               Certificate) filed as Exhibits 1 and 2 to Registrant's
               Registration Statement on Form 8-A, dated May 24, 1988, is
               incorporated herein by reference.

No. 10-1       The Mercantile Bancorporation Inc. 1987 Stock Option Plan, as
               amended, filed as Exhibit 10-3 to Registrant's Report on Form
               10-K for the year ended December 31, 1989 (Commission File No.
               1-11792), is incorporated herein by reference.

No. 10-2       The Mercantile Bancorporation Inc. Executive Incentive
               Compensation Plan, filed as Appendix C to Registrant's
               definitive Proxy Statement for the 1994 Annual Meeting of
               Shareholders, is incorporated herein by reference.

No. 10-3       The Mercantile Bancorporation Inc. Employee Stock Purchase
               Plan, filed as Exhibit 10-7 to Registrant's Report on Form 10-K
               for the year ended December 31, 1989 (Commission File No.
               1-11792), is incorporated herein by reference.

No. 10-4       The Mercantile Bancorporation Inc. 1991 Employee Incentive
               Plan, filed as Exhibit 10-7 to Registrant's Report on Form 10-K
               for the year ended December 31, 1990 (Commission File No.
               1-11792), is incorporated herein by reference.

No. 10-5       Amendment Number One to the Mercantile Bancorporation Inc. 1991
               Employee Incentive Plan, filed as Exhibit 10-6 to Registrant's
               Report on Form 10-K for the year ended December 31, 1994, is
               incorporated herein by reference.





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<PAGE> 4

<CAPTION>
Exhibit No.                          Description
----------                           -----------
<C>            <S>
No. 10-6       The Mercantile Bancorporation Inc. 1994 Stock Incentive Plan,
               filed as Appendix B to Registrant's definitive Proxy Statement
               for the 1994 Annual Meeting of Shareholders, is incorporated
               herein by reference.

No. 10-7       The Mercantile Bancorporation Inc. 1994 Stock Incentive Plan
               for Non-Employee Directors, filed as Appendix E to Registrant's
               definitive Proxy Statement for the 1994 Annual Meeting of
               Shareholders, is incorporated herein by reference.

No. 10-8       The Mercantile Bancorporation Inc. Voluntary Deferred
               Compensation Plan, filed as Appendix D to Registrant's
               definitive Proxy Statement for the 1994 Annual Meeting of
               Shareholders, is incorporated herein by reference.

No. 10-9       Form of Employment Agreement for Thomas H. Jacobsen, as
               amended, filed as Exhibit 10-8 to Registrant's Report on Form
               10-K for the year ended December 31, 1989 (Commission File No.
               1-11792), is incorporated herein by reference.

No. 10-10      Form of Change of Control Employment Agreement for John W.
               McClure, W. Randolph Adams, John Q. Arnold and Certain Other
               Executive Officers, filed as Exhibit 10-10 to Registrant's
               Report on Form 10-K for the year ended December 31, 1989
               Commission File No. 1-11792), is incorporated herein by
               reference.

No. 10-11      Agreement and Plan of Reorganization dated August 4, 1995, by
               and between Mercantile Bancorporation Inc. and Hawkeye
               Bancorporation, filed as Exhibit 2.1 to Registrant's
               Registration Statement No. 33-63609, is incorporated herein by
               reference.

No. 10-12      Mercantile Bancorporation Inc. Supplemental Retirement Plan,
               filed as Exhibit 10-12 to Registrant's Report on Form 10-K for
               the year ended December 31, 1992, is incorporated herein by
               reference.

No. 10-13      Agreement and Plan of Reorganization dated October 27, 1996,
               and between Mercantile Bancorporation Inc., Ameribanc, Inc. and
               Mark Twain Bancshares, Inc., filed as Exhibit 2.1 to
               Registrant's Report on Form 8-K filed on November 6, 1996, is
               incorporated herein by reference.

No. 10-14      Amendment to Agreement and Plan of Reorganization, dated
               January 24, 1997, by and among Registrant, Ameribanc, Inc. and
               Mark Twain Bancshares, Inc., filed as Exhibit 10-16 to
               Amendment No. 2 to Registrant's Registration Statement No.
               33-17757, is incorporated herein by reference.

No. 10-15      Stock Option Agreement, dated October 27, 1996, by and between
               Mercantile Bancorporation Inc., as grantee, and Mark Twain
               Bancshares, Inc., as issuer, filed as Exhibit 2.2 to
               Registrant's Report on Form 8-K filed on November 6, 1996, is
               incorporated herein by reference.

No. 10-16      Agreement and Plan of Reorganization, dated December 22, 1996,
               by and between Mercantile Bancorporation Inc. and Roosevelt
               Financial Group, Inc., filed as Exhibit 2.1 to Registrant's
               Report on Form 8-K filed on December 30, 1996, is incorporated
               herein by reference.




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<CAPTION>
Exhibit No.                           Description
----------                            -----------
<C>            <S>
No. 10-17      Stock Option Agreement, dated December 22, 1996, by and between
               Mercantile Bancorporation Inc., as grantee, and Roosevelt
               Financial Group, Inc., as issuer, filed as Exhibit 2.1 to
               Registrant's Report on Form 8-K filed on December 30, 1996, is
               incorporated herein by reference.

No. 21         Subsidiaries of the Registrant as of January 31, 1997.

No. 23         Consent of KPMG Peat Marwick LLP.

No. 23-1       Consent of KPMG Peat Marwick LLP (relating to report dated June
               20, 1997, Mercantile Bancorporation Inc. Horizon Investment and
               Savings Plan and Trust Financial Statements.)

No. 24         Power of Attorney (on signature page).

No. 27         Financial Data Schedule.

No. 99         Report of the Independent Auditors KPMG Peat Marwick LLP dated
               June 20, 1997; Statements of Assets Available for Plan Benefits
               of the Mercantile Bancorporation Inc. Horizon Investment and
               Savings Plan and Trust at December 31, 1996 and 1995;
               Statements of Changes in Assets Available for Plan Benefits for
               the years then ended; and the Notes and Schedules thereto.
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                                  SIGNATURE

         Pursuant to the requirements of the Securities Exchange Act of 1934,
the Registrant has duly caused this amendment to be signed on its behalf by
the undersigned, thereunto duly authorized.




                                          MERCANTILE BANCORPORATION INC.
                                          (Registrant)




Date: June 27, 1997                       By: /s/JOHN Q. ARNOLD
                                             -----------------------------
                                             John Q. Arnold
                                             Senior Executive Vice President
                                             and Chief Financial Officer

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                                   10-K/A
<TABLE>
                                EXHIBIT INDEX
                                -------------
<CAPTION>


Exhibit No.                            Description
----------                             -----------
<C>            <S>
No. 23-1       Consent of KPMG Peat Marwick LLP (relating to report dated June
               20, 1997, Mercantile Bancorporation Inc. Horizon Investment and
               Savings Plan and Trust Financial Statements.)

No. 99         Report of the Independent Auditors KPMG Peat Marwick LLP dated
               June 20, 1997; Statements of Assets Available for Plan Benefits
               of the Mercantile Bancorporation Inc. Horizon Investment and
               Savings Plan and Trust as of December 31, 1996 and 1995;
               Statements of Changes in Assets Available for Plan Benefits for
               the years then ended; and the Notes and Schedules thereto.






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