SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                                    FORM 11-K



(Mark One)
         [X]      ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE
                  SECURITIES EXCHANGE ACT OF 1934

                  For the fiscal year ended December 31, 2003


         [ ]      TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE
                  SECURITIES EXCHANGE ACT OF 1934

                  For the transition period from ________ to _______


Commission File Number 0-3683

Full title of the Plan and the address of the Plan,  if  different  from that of
the issuer named below:

                              Trustmark 401(k) Plan


Name of issuer of the  securities  held  pursuant to the Plan and the address of
its principal executive office:

                              Trustmark Corporation
                              248 E. Capitol Street
                           Jackson, Mississippi 39201




                             TRUSTMARK 401(K) PLAN

                       Financial Statements and Schedule

                           December 31, 2003 and 2002

        (Report of Independent Registered Public Accounting Firm Thereon)


                              TRUSTMARK 401(K) PLAN


                   Index to Financial Statements and Schedule


Report of Independent Registered Public Accounting Firm

Statements of Net Assets Available for Benefits as of December 31, 2003 and 2002

Statement of Changes in Net Assets Available for Benefits for the year ended
     December 31, 2003 and 2002

Notes to Financial Statements

Supplemental Schedule:

Schedule H, Line 4i - Schedule of Assets (Held at End of Year) as of December
31, 2003

All other schedules are omitted because there is no information to report.


             Report of Independent Registered Public Accounting Firm


The Plan Administrator
Trustmark 401(k) Plan:


We have audited the accompanying statements of net assets available for benefits
of Trustmark  401(k) Plan (the Plan) as of December  31, 2003 and 2002,  and the
related  statement of changes in net assets available for benefits for the years
then ended.  These  financial  statements are the  responsibility  of the Plan's
management.  Our  responsibility  is to express  an  opinion on these  financial
statements based on our audits.

We conducted our audits in accordance  with the standards of the Public  Company
Accounting Oversight Board (United States). Those standards require that we plan
and perform the audit to obtain reasonable assurance about whether the financial
statements are free of material misstatement.  An audit includes examining, on a
test basis,  evidence  supporting  the amounts and  disclosures in the financial
statements.  An audit also includes assessing the accounting principles used and
significant  estimates  made by  management,  as well as evaluating  the overall
financial  statement  presentation.   We  believe  that  our  audit  provides  a
reasonable basis for our opinion.

In our opinion,  the financial  statements  referred to above present fairly, in
all material  respects,  the net assets available for benefits of the Plan as of
December 31, 2003 and 2002, and the changes in net assets available for benefits
for the years then ended in  conformity  with  accounting  principles  generally
accepted in the United States of America.

Our audits  were  performed  for the  purpose of forming an opinion on the basic
financial statements taken as a whole. The supplemental schedule of assets (held
at end of year) is not a required part of the basic financial  statements but is
supplementary  information  required  by the  Department  of  Labor's  Rules and
Regulations for Reporting and Disclosure  under the Employee  Retirement  Income
Security Act of 1974. The  supplemental  schedule is the  responsibility  of the
Plan's management.  The supplemental schedule has been subjected to the auditing
procedures  applied in the audit of the basic 2003 financial  statements and, in
our opinion,  is fairly stated in all material respects in relation to the basic
2003 financial statements taken as a whole.

                                        /s/ KPMG LLP


Jackson, Mississippi
June 7, 2004





                              TRUSTMARK 401(K) PLAN
                 Statements of Net Assets Available for Benefits
                           December 31, 2003 and 2002

                                                          2003          2002
                                                      ------------  ------------
Receivables:
   Employer contributions                             $    231,240  $    123,895
   Participants contributions                              191,042       193,956
   Investment proceeds                                     240,014           -
                                                      ------------  ------------
            Total receivables                              662,296       317,851

Investments, at fair value:
   Money market accounts                                14,944,873    14,377,264
   Fixed income mutual funds                             4,989,877     6,094,106
   Common stock of Trustmark Corporation                55,284,620    53,648,075
   Equity mutual funds                                  34,381,716    23,135,259
                                                      ------------  ------------
            Total investments                          109,601,086    97,254,704
                                                      ------------  ------------
            Net assets available for benefits         $110,263,382  $ 97,572,555
                                                      ============  ============
See accompanying notes to financial statements.



                              TRUSTMARK 401(K) PLAN
            Statement of Changes in Net Assets Available for Benefits
                     Years ended December 31, 2003 and 2002

                                                         2003          2002
                                                     ------------  ------------
    Contributions:
       Employer                                      $  3,178,679  $  2,870,482
       Participants                                     5,138,254     4,935,396
                                                     ------------  ------------
              Total contributions                       8,316,933     7,805,878
                                                     ------------  ------------
    Net investment income:
       Net appreciation (depreciation) in
         fair value of investments                     17,159,125    (5,022,263)
       Interest income                                  1,627,766       540,317
       Dividend income                                  1,347,219     1,715,667
                                                     ------------  ------------
              Net investment income (loss)             20,134,110    (2,766,279)
                                                     ------------  ------------
    Benefits paid to participants                     (15,592,475)   (9,609,509)
    Administrative fees                                  (167,741)     (180,421)
                                                     ------------  ------------
              Net increase (decrease) in net
                assets available for benefits          12,690,827    (4,750,331)

Net assets available for benefits:
    Beginning of year                                  97,572,555   102,322,886
                                                     ------------  ------------
    End of year                                      $110,263,382  $ 97,572,555
                                                     ============  ============
See accompanying notes to financial statements.



                              TRUSTMARK 401(K) PLAN
                          Notes to Financial Statements
                           December 31, 2003 and 2002


(1)  Plan Description

     The following description of Trustmark 401(k) Plan (the Plan) provides only
     general information.  Participants should refer to the Plan agreement for a
     more complete description of the Plan's provisions.

     (a)  General

          The Plan is a defined  contribution plan established for the employees
          of Trustmark  Corporation  (the Company) and certain other  associated
          companies.  The Plan provides  eligibility  for  participation  on the
          first day of the month  following  the  completion  of at least  1,000
          hours  of  service  during  the  twelve-month  period  ending  on  the
          anniversary of a person's employment commencement date.

     (b)  Plan Administration

          The Plan's record  keeping  functions  are handled by Nationwide  Life
          Insurance  Company and Nationwide  Trust Company.  Trustmark  National
          Bank serves as the Plan's trustee.  The plan administrator and sponsor
          is Trustmark  Corporation,  parent company of Trustmark National Bank.
          Prior to January  31,  2002,  Bysis Plan  Services  and  Frontier  and
          Reliance Trusts served as record keeper and trustees, respectively.

     (c)  Participants Contributions

          The Plan  allows  participants  to make  voluntary  before-tax  salary
          deferral  contributions,  through  payroll  deductions,  to separately
          invested  funds in  accordance  with  Section  401(k) of the  Internal
          Revenue Code. If certain requirements of Internal Revenue Code Section
          401(k) are not met in Plan operation,  the salary deferral  agreements
          of  participants  may, on a  nondiscriminatory  and uniform basis,  be
          amended or  revoked  to  preserve  the  qualified  status of the Plan.
          Voluntary  after-tax  contributions  by participants  are not allowed.
          Participants  may direct  investment of their voluntary  contributions
          among several investment options.

          Participants   may  elect  to   contribute   up  to  25%  of  eligible
          compensation   each  period,   subject  to   regulatory   limitations.
          Additionally,   rollover   contributions  from  individual  retirement
          accounts or other qualified plans are allowed.

          In 2002, the Plan was amended,  whereby,  participants who were age 50
          years or older by the end of calendar  year were able to make catch-up
          contributions to the Plan. Catch-up  contributions  represent employee
          compensation  deferrals in excess of certain plan limits and statutory
          limits including IRS annual deferral  limits.  The IRS annual deferral
          limits and annual  catch-up  contribution  limits are indicated in the
          following schedule:

                                                                   Catch-up
          Calendar year            Deferral limit             contribution limit
          -------------            ---------------            ------------------
              2002                     $11,000                      $1,000
              2003                      12,000                       2,000
              2004                      13,000                       3,000
              2005                      14,000                       4,000
              2006                      15,000                       5,000
           Thereafter              Indexed in $500              Indexed in $500
                                     increments                   increments


     (d)  Employer Contributions

          All  employee  contributions  are matched by the employer at a rate of
          100% of the first 3% and 50% of the next 3% of  covered  compensation.
          The employer may also make discretionary contributions.

     (e)  Allocations

          Participant and employer  contributions are allocated directly to each
          participant's account in accordance with the individual  participant's
          elections.  Forfeitures of nonvested employer  discretionary  accounts
          are used to reduce the employer  match  contribution.  During 2003 and
          2002,  the Plan  utilized  $23,192  and  $154,037  in  forfeitures  as
          employer contributions, respectively.

     (f)  Vesting

          Participants are immediately  vested in their voluntary  contributions
          and employer matching  contributions  and the investment  earnings and
          losses  thereon.  Participants  vest  in  the  employer  discretionary
          contributions as shown in the following schedule:

                    Years vesting service  Vested percentage
                    ---------------------  -----------------
                         Less than 5                 0%
                         5 or more                 100%

          In case of termination  of the Plan,  the value of each  participant's
          share  of the  Plan  becomes  fully  vested  as of the  date  of  such
          termination.  In  addition,  a  participant  is fully  vested  in such
          participant's share of the Plan upon achieving the age of sixty-five.

     (g)  Payment of Benefits

          On  retirement,  death,  disability,  or  termination  of  service,  a
          participant may elect to receive a lump-sum  distribution equal to his
          or her vested account balance or a life annuity. In addition, hardship
          distributions are permitted if certain criteria are met.

     (h)  Plan Termination

          Although it has not expressed any intent to do so, the Company has the
          right under the Plan to discontinue its  contributions at any time and
          to terminate the Plan subject to the provisions of ERISA.  However, no
          such action may deprive any participant or beneficiary  under the Plan
          of any vested benefit.

(2)  Significant Accounting Policies

     (a)  Basis of Presentation

          The Plan's  financial  statements are prepared using the accrual basis
          of  accounting,  with the exception of the payment of benefits,  which
          are recognized as a reduction in the net assets available for benefits
          of the Plan as they are disbursed to participants. Purchases and sales
          of securities are recorded on a trade-date basis.


     (b)  Use of Estimates

          The preparation of financial  statements in conformity with accounting
          principles generally accepted in the United States of America requires
          management to make estimates and assumptions  that affect the reported
          amounts  of  net  assets  and  changes  therein,   and  disclosure  of
          contingent  assets and  liabilities.  Actual results could differ from
          those estimates.

     (c)  Valuation of Investments

          Investments  are stated at fair value.  The fair value of mutual funds
          and other  securities  traded on a national  securities  exchange  are
          valued at the closing  quoted market price on the last business day of
          the year.

     (d)  Net Appreciation (Depreciation) in Fair Value of Investments

          Net  appreciation  (depreciation)  in fair  value of  investments,  as
          recorded  in the  accompanying  statement  of  changes  in net  assets
          available for benefits,  includes changes in fair value of investments
          acquired, sold, or held during the year.

     (e)  Administrative Fees

          Administrative  fees are paid by the Plan.  All other fees,  including
          professional fees, are paid by the Company.

(3)  Investments

     The fair value of individual  investments  that represent 5% or more of the
     Plan's net assets as of December 31, 2003 and 2002 are as follows:

                                                            December 31,
                                                       -------------------------
                                                           2003          2002
                                                       -----------   -----------
     Investment at fair value as determined
       by quoted market price:
        Common stock of Trustmark Corporation          $55,284,620   $53,648,075
        Performance Funds Trust Mutual Funds:
           Large-Cap Equity Fund                         7,120,723     6,047,890
           Mid-Cap Equity Fund                           7,402,858     5,484,933
     Investments at cost, which approximates
       fair value:
        Federated Capital Preservation Fund             13,027,583    13,768,069

     During 2003 and 2002, the Plan's investments  (including investments bought
     and sold,  as well as held during the year)  appreciated  (depreciated)  in
     value as follows:

                                                             December 31,
                                                      -------------------------
                                                          2003          2002
                                                      -----------   -----------

     Investments at fair value as determined
       by quoted market price:
        Trustmark Corporation Stock Fund              $10,791,486   $ 1,419,642
        Mutual funds                                    6,367,639    (6,441,905)
                                                      -----------   -----------
          Net appreciation (depreciation) in
            fair value of investments                 $17,159,125   $(5,022,263)
                                                      ===========   ===========

(4)  Income Tax Status

     The Internal  Revenue  Service has determined and informed the Company by a
     letter  dated  November  19,  2001,  that the Plan and  related  trust  are
     designed in accordance  with  applicable  sections of the Internal  Revenue
     Code (IRC).  The Plan has been amended since  receiving  the  determination
     letter.  However, the plan administrator and the Plan's tax counsel believe
     that the Plan is designed and is  currently  being  operated in  compliance
     with the applicable requirements of the IRC.


(5)  Related Parties

     Trustmark   National  Bank  serves  as  the  investment   advisor  for  the
     Performance Funds Trust Mutual Funds.  Trustmark  Corporation is the parent
     Company of Trustmark National Bank.  Trustmark National Bank also serves as
     the Plan's trustee.

(6)  Reconciliation of Financial Statements to Form 5500

     As of December  31,  2003,  the Plan had $468 of pending  distributions  to
     participants who elected to withdraw from the Plan. This amount is recorded
     as a  liability  in the  Plan's  Form  5500;  however,  this  amount is not
     recorded  as a  liability  in the  accompanying  statement  of  net  assets
     available for benefits in accordance with accounting  principles  generally
     accepted in the United States of America.

     The following is a reconciliation  of benefits paid to participants per the
     accompanying  financial statements to the Form 5500 as filed by the Company
     for the year ended December 31, 2003:

                                                                      Benefits
                                                                        paid
                                                                    -----------
     Per accompanying financial statements                          $15,592,475
     2003 amounts pending distribution to participants                      468
                                                                    -----------
                 Per Form 5500                                      $15,592,943
                                                                    ===========

     The following table is a reconciliation  of benefits payable and net assets
     available  for benefits per the  accompanying  financial  statements to the
     Form 5500 as filed by the Company for the year ended December 31, 2003:

                                                                    Net assets
                                                        Benefit   available for
                                                        payable   plan benefits
                                                        -------   -------------
     Per accompanying financial statements              $    -    $ 110,263,382
     2003 amounts pending distribution to participants      468            (468)
                                                        -------   -------------
                 Per Form 5500                          $   468   $ 110,262,914
                                                        =======   =============

(7)  Contingencies

     The Company and its  subsidiaries  are parties to lawsuits and other claims
     that arise in the ordinary course of business.  Some of the lawsuits assert
     claims  related to various  business  activities;  and some of the lawsuits
     allege  substantial  claims  for  damages.  The cases are being  vigorously
     contested.  In  the  regular  course  of  business,   management  evaluates
     estimated losses or costs related to litigation,  and provision is made for
     anticipated  losses  whenever  management  believes  that such  losses  are
     probable and can be reasonably  estimated.  At the present time, management
     believes,  based on the advice of legal counsel,  that the final resolution
     of  pending  legal  proceedings  will not  have a  material  impact  on the
     Company's  or the  Plan's  consolidated  financial  position  or results of
     operations.

(8)  Subsequent Events

     Effective  January 1, 2004,  the Plan was  amended to include  several  new
     provisions. The Plan will provide eligibility for participation in elective
     deferrals by employees on the first day of the month after thirty (30) days
     of  employment.  The amendment  will have no effect on the  eligibility  of
     employees to receive  employer  contributions.  Also  effective  January 1,
     2004,  participants will be 100% vested in all employer  contributions made
     on their behalf including those non-vested  contributions  remaining in the
     Plan on January 1, 2004,  but deposited by the employer at an earlier date.
     The Plan will also provide for  participants  the  opportunity  to annually
     elect that cash  dividends  paid on employer stock either (1) be reinvested
     in shares of employer stock, or (2) be paid to the participant's account in
     cash.



                              TRUSTMARK 401(K) PLAN
                       Plan Sponsor: Trustmark Corporation
                          Plan Sponsor: EIN 64-0471500
                                Plan Number: 002
                        Schedule H, Line 4i - Schedule of
                          Assets (Held at End of Year)
                                December 31, 2003
                                                                       Current
     Identity of issuer                    Description                  value
---------------------------  -------------------------------------- ------------
 Money market account:
    Federated                Capital Preservation Fund              $ 13,027,583
    Gartmore                 Money Market Inst. Fund                   1,202,728
    AllianceBernstein        Inst.Money Market Fund                      714,562
 Fixed income mutual funds:
*   Performance Funds Trust  Short Term Govt. Inst.Fund                1,696,437
*   Performance Funds Trust  Intermediate Term Govt. Inst.Fund         1,896,409
    Dreyfus                  GNMA Fund                                   418,041
    PIMCO                    Total Return Fund                           978,990
 Common stock fund:
*   Trustmark Corporation    Common Stock Fund                        55,284,620
 Equity mutual funds:
*   Performance Funds Trust  Leader's Equity Fund                        472,015
*   Performance Funds Trust  Large-Cap Equity Fund                     7,120,723
*   Performance Funds Trust  Mid-Cap Equity Fund                       7,402,858
    Dreyfus                  Mid-Cap Value Fund                        3,286,271
    Franklin                 Balance Sheet Investment Fund             1,452,726
    Franklin                 Mutual Discovery Fund                       842,783
    Gartmore                 Inv. Destinations Aggr. Svc. Fund           416,558
    Gartmore                 Inv. Destinations Cons. Svc. Fund            28,607
    Gartmore                 Inv. Destinations Mod. Svc. Fund            273,874
    Gartmore                 Inv. Destinations Mod. Aggr. Svc. Fund      581,460
    Gartmore                 Inv. Destinations Mod. Cons. Svc. Fund       92,353
    Goldman Sachs            CORE Small Cap. Equity Fund               3,518,963
    INVESCO                  Dynamics Inv. Fund                          200,451
    Neuberger                Neuberger Berman Genesis Trust            2,403,864
    Oppenheimer              Global Fund                                 763,086
    Van Kampen               Equity & Income Fund                      2,632,090
    Van Kampen               Emerging Growth Fund                      1,341,359
    Templeton                Foreign Fund                              1,551,675
                                                                    ------------
                                                                    $109,601,086
                                                                    ============

* Denotes related party based on the following relationships:
        Trustmark National Bank serves as investment advisor for Performance
        Funds Trusts; Trustmark Corporation is the parent company of Trustmark
        National Bank.

See accompanying independent auditors' report.



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

                                    Trustmark 401(k) Plan
                                    Trustmark Corporation, Plan Administrator

                                    By: /s/ Louis E. Greer
                                    -------------------
                                    Louis E. Greer
                                    Chief Accounting Officer

                                    June 24, 2004