<PAGE>

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                       POST EFFECTIVE AMENDMENT NO. 1 TO
                                    FORM S-8
                             REGISTRATION STATEMENT
                                     Under
                           THE SECURITIES ACT OF 1933

                             Trustmark Corporation
             (Exact name of registrant as specified in its charter)

         Mississippi                                                  64-0471500
(State or other jurisdiction of                                        (IRS EIN)
incorporation or organization)

               248 E. Capitol Street, Jackson, Mississippi 39201
              (Address of principal executive offices) (Zip Code)

              Trustmark Corporation 1997 Long Term Incentive Plan
                            (full title of the plan)

                                 LOUIS E. GREER
                                   Controller
                            Trustmark National Bank
                             248 E. Capitol Street
                               Jackson, MS 39201
                       (601) 949-2310 Fax: (601) 949-6871

                (Name, address including zip code and telephone
               number, including area code, of agent for service)

                        Copies of all correspondence to:

                              Robert D. Drinkwater
                    Brunini, Grantham, Grower & Hewes, PLLC
                             Post Office Drawer 119
                               Jackson, MS 39205
                       (601) 948-3101 Fax: (601) 960-6902


<PAGE>

                        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       PER SHARE     PRICE            FEE
----------          ----------       ---------     -----------      ------------
Common Stock          300,000         $ 22.78      $ 6,834,000        $1,805
$0.00 par value
per share

         Registration  fee has been  calculated in  accordance  with Rule 457(h)
under the  Securities  Act of 1933 and is based upon the highest  price at which
currently issued options may be exercised.

         If any securities  being registered on this form are to be offered on a
delayed or continuous  basis  pursuant to Rule 415 under the  Securities  Act of
1933, check the following box. [x]

Explanation

         This Post-Effective  Amendment No. 1 is being filed to register 300,000
additional  shares  issuable  pursuant to  Registrant's 1997 Long Term Incentive
Plan.  Registrant initially registered 300,000 shares pursuant to a registration
statement  on Form S-8  which  became  effective  September  17,1997  (File  No.
333-35889).  Effective March 30, 1998,  Registrant's  shares were split 2 for 1,
increasing  the number of  registered  shares to 600,000.  With this  amendment,
there will be a total of 900,000 shares registered.

         The  contents of the earlier  Registration  Statement on Form S-8 (File
No. 333-35889) amended hereby are incorporated herein by reference.


Item 8.  Exhibits.

      5.1  Opinion and Consent  of  Brunini, Grantham, Grower & Hewes  as to the
           legality of the issuance of the shares.

     23.1  Consent of Arthur Andersen LLP

<PAGE>

                                   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 Jackson and State of Mississippi on the 13th day
of June, 2000.

                              TRUSTMARK CORPORATION
BY:   /s/ Richard G. Hickson               BY:   /s/ Gerard R. Host
      ----------------------                     -----------------
      Richard G. Hickson                         Gerard R. Host
      President & Chief                          Treasurer (Principal
      Executive Officer                          Financial & Accounting
                                                 Officer)

DATE: June 13, 2000                        DATE: June 13, 2000

<PAGE>

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

DATE: June 13, 2000                  BY:/s/ J. Kelly Allgood
                                        ---------------------------------------
                                        J. Kelly Allgood, Director

DATE: June 13, 2000                  BY:/s/ Reuben V. Anderson
                                        ---------------------------------------
                                        Reuben V. Anderson, Director

DATE: June 13, 2000                  BY:/s/ Adolphus B. Baker
                                        ---------------------------------------
                                        Adolphus B. Baker, Director

DATE: June 13, 2000                  BY:/s/ John L. Black, Jr.
                                        ---------------------------------------
                                        John L. Black, Jr., Director

DATE: June 13, 2000                  BY:/s/ William C. Deviney
                                        ---------------------------------------
                                        William C. Deviney, Jr., Director

DATE: June 13, 2000                  BY:/s/ D.G. Fountain
                                        ---------------------------------------
                                        D.G. Fountain, Jr., Director

DATE: June 13, 2000                  BY:/s/ C. Gerald Garnett
                                        ---------------------------------------
                                        C. Gerald Garnett, Director

DATE: June 13, 2000                  BY:/s/ Richard G. Hickson
                                        ---------------------------------------
                                        Richard G. Hickson, President &
                                        Chief Executive Officer and Director

DATE: June 13, 2000                  BY:/s/ Matthew L. Holleman
                                        ---------------------------------------
                                        Matthew L. Holleman III, Director

DATE: June 13, 2000                  BY:/s/ Gerard R. Host
                                        ---------------------------------------
                                        Gerard R. Host, Treasurer (Principal
                                        Financial & Accounting Officer) and
                                        Director

DATE: June 13, 2000                  BY:/s/ Fred A. Jones
                                        ---------------------------------------
                                        Fred A. Jones, Director

<PAGE>

DATE: June 13, 2000                  BY:/s/ T.H. Kendall III
                                        ---------------------------------------
                                        T.H. Kendall III, Chairman of the
                                        Board and Director

DATE: June 13, 2000                  BY:/s/ Larry L. Lambiotte
                                        ---------------------------------------
                                        Larry L. Lambiotte, Director

DATE: June 13, 2000                  BY:/s/ Donald E. Meiners
                                        ---------------------------------------
                                        Donald E. Meiners, Director

DATE: June 13, 2000                  BY:/s/ William Neville
                                        ---------------------------------------
                                        William Neville III, Director

DATE: June 13, 2000                  BY:/s/ Richard H. Puckett
                                        ---------------------------------------
                                        Richard H. Puckett, Director

DATE: June 13, 2000                  BY:/s/ William K. Ray
                                        ---------------------------------------
                                        William K. Ray, Director

DATE: June 13, 2000                  BY:/s/ Charles W. Renfrow
                                        ---------------------------------------
                                        Charles W. Renfrow, Director

DATE: June 13, 2000                  BY:/s/ Harry M. Walker
                                        ---------------------------------------
                                        Harry M. Walker, Secretary and
                                        Director

DATE: June 13, 2000                  BY:/s/ LeRoy G. Walker, Jr.
                                        ---------------------------------------
                                        LeRoy G. Walker, Jr., Director

DATE: June 13, 2000                  BY:/s/ Paul H. Watson, Jr.
                                        ---------------------------------------
                                        Paul H. Watson, Jr., Director

DATE: June 13, 2000                  BY:/s/ Kenneth W. Williams
                                        ---------------------------------------
                                        Kenneth W. Williams, Director

DATE:                                BY:---------------------------------------
                                        Allen Wood, Jr., Director

<PAGE>

                    EXHIBIT INDEX

Exhibit Number                              Description
--------------           -------------------------------------------------------
     5.1                 Option and Consent of Brunini, Grantham, Grower & Hewes
    23.1                 Consent of Arthur Andersen LLP
[{"type": "S-8", "sequence": "1", "filename": "0001.txt", "description": "FORM S-8 OPTION SHARES", "secsgml_size_bytes": 10268}]
{"company-data": {"conformed-name": "TRUSTMARK CORP", "cik": "0000036146", "assigned-sic": "6021", "irs-number": "640471500", "state-of-incorporation": "MS", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-39786", "film-number": "658466"}, "business-address": {"street1": "248 E CAPITOL ST", "street2": "P O BOX 291", "city": "JACKSON", "state": "MS", "zip": "39201", "phone": "6013545111"}, "mail-address": {"street1": "248 EAST CAPITOL STREET", "city": "JACKSON", "state": "MS", "zip": "39201"}, "former-company": {"former-conformed-name": "FIRST CAPITAL CORP", "date-changed": "19900513"}}
SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                       POST EFFECTIVE AMENDMENT NO. 1 TO
                                    FORM S-8
                             REGISTRATION STATEMENT
                                     Under
                           THE SECURITIES ACT OF 1933

                             Trustmark Corporation
             (Exact name of registrant as specified in its charter)

         Mississippi                                                  64-0471500
(State or other jurisdiction of                                        (IRS EIN)
incorporation or organization)

               248 E. Capitol Street, Jackson, Mississippi 39201
              (Address of principal executive offices) (Zip Code)

              Trustmark Corporation 1997 Long Term Incentive Plan
                            (full title of the plan)

                                 LOUIS E. GREER
                                   Controller
                            Trustmark National Bank
                             248 E. Capitol Street
                               Jackson, MS 39201
                       (601) 949-2310 Fax: (601) 949-6871

                (Name, address including zip code and telephone
               number, including area code, of agent for service)

                        Copies of all correspondence to:

                              Robert D. Drinkwater
                    Brunini, Grantham, Grower & Hewes, PLLC
                             Post Office Drawer 119
                               Jackson, MS 39205
                       (601) 948-3101 Fax: (601) 960-6902
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       PER SHARE     PRICE            FEE
----------          ----------       ---------     -----------      ------------
Common Stock          300,000         $ 22.78      $ 6,834,000        $1,805
$0.00 par value
per share

         Registration  fee has been  calculated in  accordance  with Rule 457(h)
under the  Securities  Act of 1933 and is based upon the highest  price at which
currently issued options may be exercised.

         If any securities  being registered on this form are to be offered on a
delayed or continuous  basis  pursuant to Rule 415 under the  Securities  Act of
1933, check the following box. [x]

Explanation

         This Post-Effective  Amendment No. 1 is being filed to register 300,000
additional  shares  issuable  pursuant to  Registrant's 1997 Long Term Incentive
Plan.  Registrant initially registered 300,000 shares pursuant to a registration
statement  on Form S-8  which  became  effective  September  17,1997  (File  No.
333-35889).  Effective March 30, 1998,  Registrant's  shares were split 2 for 1,
increasing  the number of  registered  shares to 600,000.  With this  amendment,
there will be a total of 900,000 shares registered.

         The  contents of the earlier  Registration  Statement on Form S-8 (File
No. 333-35889) amended hereby are incorporated herein by reference.

Item 8.  Exhibits.

      5.1  Opinion and Consent  of  Brunini, Grantham, Grower & Hewes  as to the
           legality of the issuance of the shares.

     23.1  Consent of Arthur Andersen LLP
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 Jackson and State of Mississippi on the 13th day
of June, 2000.

                              TRUSTMARK CORPORATION
BY:   /s/ Richard G. Hickson               BY:   /s/ Gerard R. Host
      ----------------------                     -----------------
      Richard G. Hickson                         Gerard R. Host
      President & Chief                          Treasurer (Principal
      Executive Officer                          Financial & Accounting
                                                 Officer)

DATE: June 13, 2000                        DATE: June 13, 2000
Pursuant to the requirements of the Securities Act of 1933, as amended,
this  Registration  Statement  has been signed by the  following  persons in the
capacities and on the date indicated.

DATE: June 13, 2000                  BY:/s/ J. Kelly Allgood
                                        ---------------------------------------
                                        J. Kelly Allgood, Director

DATE: June 13, 2000                  BY:/s/ Reuben V. Anderson
                                        ---------------------------------------
                                        Reuben V. Anderson, Director

DATE: June 13, 2000                  BY:/s/ Adolphus B. Baker
                                        ---------------------------------------
                                        Adolphus B. Baker, Director

DATE: June 13, 2000                  BY:/s/ John L. Black, Jr.
                                        ---------------------------------------
                                        John L. Black, Jr., Director

DATE: June 13, 2000                  BY:/s/ William C. Deviney
                                        ---------------------------------------
                                        William C. Deviney, Jr., Director

DATE: June 13, 2000                  BY:/s/ D.G. Fountain
                                        ---------------------------------------
                                        D.G. Fountain, Jr., Director

DATE: June 13, 2000                  BY:/s/ C. Gerald Garnett
                                        ---------------------------------------
                                        C. Gerald Garnett, Director

DATE: June 13, 2000                  BY:/s/ Richard G. Hickson
                                        ---------------------------------------
                                        Richard G. Hickson, President &
                                        Chief Executive Officer and Director

DATE: June 13, 2000                  BY:/s/ Matthew L. Holleman
                                        ---------------------------------------
                                        Matthew L. Holleman III, Director

DATE: June 13, 2000                  BY:/s/ Gerard R. Host
                                        ---------------------------------------
                                        Gerard R. Host, Treasurer (Principal
                                        Financial & Accounting Officer) and
                                        Director

DATE: June 13, 2000                  BY:/s/ Fred A. Jones
                                        ---------------------------------------
                                        Fred A. Jones, Director
DATE: June 13, 2000                  BY:/s/ T.H. Kendall III
                                        ---------------------------------------
                                        T.H. Kendall III, Chairman of the
                                        Board and Director

DATE: June 13, 2000                  BY:/s/ Larry L. Lambiotte
                                        ---------------------------------------
                                        Larry L. Lambiotte, Director

DATE: June 13, 2000                  BY:/s/ Donald E. Meiners
                                        ---------------------------------------
                                        Donald E. Meiners, Director

DATE: June 13, 2000                  BY:/s/ William Neville
                                        ---------------------------------------
                                        William Neville III, Director

DATE: June 13, 2000                  BY:/s/ Richard H. Puckett
                                        ---------------------------------------
                                        Richard H. Puckett, Director

DATE: June 13, 2000                  BY:/s/ William K. Ray
                                        ---------------------------------------
                                        William K. Ray, Director

DATE: June 13, 2000                  BY:/s/ Charles W. Renfrow
                                        ---------------------------------------
                                        Charles W. Renfrow, Director

DATE: June 13, 2000                  BY:/s/ Harry M. Walker
                                        ---------------------------------------
                                        Harry M. Walker, Secretary and
                                        Director

DATE: June 13, 2000                  BY:/s/ LeRoy G. Walker, Jr.
                                        ---------------------------------------
                                        LeRoy G. Walker, Jr., Director

DATE: June 13, 2000                  BY:/s/ Paul H. Watson, Jr.
                                        ---------------------------------------
                                        Paul H. Watson, Jr., Director

DATE: June 13, 2000                  BY:/s/ Kenneth W. Williams
                                        ---------------------------------------
                                        Kenneth W. Williams, Director

DATE:                                BY:---------------------------------------
                                        Allen Wood, Jr., Director
EXHIBIT INDEX

Exhibit Number                              Description
--------------           -------------------------------------------------------
     5.1                 Option and Consent of Brunini, Grantham, Grower & Hewes
    23.1                 Consent of Arthur Andersen LLP