<PAGE>
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                   FORM 10-K

                 ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d)
                     OF THE SECURITIES EXCHANGE ACT OF 1934


For the Fiscal Year Ended                                 Commission file number
   December 31, 2003                                               0-16759

                          FIRST FINANCIAL CORPORATION
             (Exact name of registrant as specified in its charter)


      INDIANA                                         35-1546989
(State of Incorporation)                    (I.R.S. Employer Identification No.)

One First Financial Plaza                               47807
   Terre Haute, IN
(Address of principal executive offices)              (Zip Code)

                 Registrant's telephone number: (812) 238-6000

        Securities registered pursuant to Section 12(b) of the Act: None

          Securities registered pursuant to Section 12(g) of the Act:

<TABLE>
<CAPTION>
TITLE OF EACH CLASS                    NAME OF EACH EXCHANGE ON WHICH REGISTERED
-------------------                    -----------------------------------------
<S>                                    <C>
Common Stock, no par value                             Nasdaq
</TABLE>

         Indicated by check mark whether the registrant (1) has filed all
reports required to be filed by Section 13 or 15(d) 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 of Registrant's knowledge, in definitive proxy or information statements
incorporated by reference in Part III of the Form 10-K or any amendment to the
form 10-K. [ ]

         Indicate by check mark whether the registrant is an accelerated filer
(as defined in Rule 12b-2 of the Act). Yes  X   No
                                           ---     ---

         As of June 30, 2003 the aggregate market value of the voting stock held
by nonaffiliates of the registrant based on the average bid and ask prices of
such stock was $337,295,810. (For purposes of this calculation, the Corporation
excluded the stock owned by certain beneficial owners and management and the
Corporation's ESOP.)

         Shares of Common Stock outstanding as of February 29, 2004--13,563,770
shares.

                      DOCUMENTS INCORPORATED BY REFERENCE

         Portions of the 2003 Annual Report to Shareholders are incorporated by
reference into Parts I and II. Portions of the Definitive Proxy Statement for
the First Financial Corporation Annual Meeting of Shareholders to be held April
21, 2004 are incorporated by reference into Part III.

<PAGE>
                        FORM 10-K CROSS-REFERENCE INDEX


<TABLE>
<CAPTION>

                                                                                                          PAGE
<S>                                                                                                       <C>
PART I

Item 1  Business ......................................................................................     2
Item 2  Properties ....................................................................................     2
Item 3  Legal Proceedings .............................................................................     2
Item 4  Submission of Matters to a Vote of Security Holders ...........................................     2

PART II

Item 5  Market for Registrant's Common Stock and Related Stockholder Matters ..........................     3
Item 6  Selected Financial Data .......................................................................     3
Item 7  Management's Discussion and Analysis of Financial Condition and Results of Operation ..........     3
Item 7A Quantitative and Qualitative Disclosures about Market Risk ....................................     3
Item 8  Financial Statements and Supplementary Data ...................................................     3
Item 9  Changes in and Disagreements with Accountants on Accounting and Financial Disclosures .........     3
Item 9A Controls and Procedures .......................................................................  3, 4

PART III

Item 10 Directors and Executive Officers of Registrant ...............................................     4
Item 11 Executive Compensation .......................................................................     4
Item 12 Security Ownership of Certain Beneficial Owners and Management and Related Shareholder Matters     4
Item 13 Certain Relationships and Related Transactions ...............................................     4
Item 14 Principal Accountant Fees and Services .......................................................     4

PART IV

Item 15 Exhibits, Financial Statement Schedules and Reports on Form 8-K ..............................     5

        Signatures ...................................................................................  6, 7
</TABLE>


                                       1

<PAGE>
                                     PART I

ITEM 1. BUSINESS

     First Financial Corporation (the "Corporation") is a financial services
holding company formed under Indiana law in 2001. The Corporation was originally
organized as a multi-bank holding company in 1984. For more information on the
Corporation's business, please refer to the following sections of the 2003
Annual Report to Shareholders:

     1. Description of services, affiliations, number of employees, and
        competition, on page 30.

     2. Information regarding supervision of the Corporation, on page 14.

     3. Details regarding competition, on page 30.

ITEM 2. PROPERTIES

     First Financial Corporation is located in a four-story office building in
downtown Terre Haute, Indiana that was first occupied in June 1988. It is leased
to First Financial Bank N.A., formerly known as Terre Haute First National Bank,
a wholly-owned subsidiary (the Bank). The Bank also owns two other facilities in
downtown Terre Haute. One is leased to another party and the other is a
50,000-square-foot building housing operations and administrative staff and
equipment. In addition, the Bank holds in fee six other branch buildings. One of
the branch buildings is a single story 36,000-square-foot building which is
located in a Terre Haute suburban area. Six other branch bank buildings are
leased by the Bank. The expiration dates on the leases are June 30, 2012, May
31, 2011, February 14, 2011, December 31, 2008, September 1, 2006, and June 30,
2004.

     Facilities of the Corporation's subsidiary, First State Bank, include its
main office in Brazil, Indiana and four branch facilities in Brazil, Clay City
and Poland, Indiana. All five buildings are held in fee by First State.

     Facilities of the Corporation's subsidiary, First Citizens State Bank of
Newport, include its main office in Newport, Indiana and three branch facilities
in Cayuga and Clinton, Indiana. All four buildings are held in fee by First
Citizens.

     Facilities of the Corporation's subsidiary, First Farmers State Bank,
include its main office in Sullivan, Indiana and seven branch facilities in
Carlisle, Dugger, Farmersburg, Hymera, Monroe City, Sandborn and Worthington,
Indiana. All eight buildings are held in fee by First Farmers.

     Facilities of the Corporation's subsidiary, First Parke State Bank, include
its main office in Rockville, Indiana and four branch facilities in Rockville,
Marshall, Montezuma and Rosedale, Indiana. All five buildings are held in fee by
First Parke.

     Facilities of the Corporation's subsidiary, First Crawford State Bank,
include its main office in Robinson, Illinois and two branch facilities in
Oblong and Sumner, Illinois. All three buildings are held in fee by First
Crawford.

     The facility of the Corporation's subsidiary, The Morris Plan Company,
includes an office facility in Terre Haute, Indiana. The building is leased by
The Morris Plan Company. The expiration date on the lease is August 31, 2008.

     Facilities of the Corporation's subsidiary, Forrest Sherer, Inc., include
its main office and one satellite office in Terre Haute, Indiana. The buildings
are held in fee by Forrest Sherer, Inc.

     Facilities of the Corporation's subsidiary, First Community Bank, N.A.,
include its main office in Olney, Illinois, and five branch facilities in Olney,
Lawrenceville, Fairfield, Newton and Charleston, Illinois. All of the buildings
are held in fee by First Community Bank, N.A., except the Olney branch, which is
leased. The expiration date on the lease is March 1, 2005.

ITEM 3. LEGAL PROCEEDINGS

     There are no material pending legal proceedings which involve the
Corporation or its subsidiaries.

ITEM 4. SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS

     None


                                       2

<PAGE>
                                    PART II

ITEM 5.  MARKET FOR REGISTRANT'S COMMON STOCK AND RELATED STOCKHOLDER MATTERS

     See "Market and Dividend Information" on page 41 of the 2003 Annual Report.
That portion of the Annual Report is incorporated by reference into this Form
10-K.

ITEM 6.  SELECTED FINANCIAL DATA

     See "Five Year Comparison of Selected Financial Data" on page 9 of the 2003
Annual Report to Shareholders. That portion of the Annual Report is incorporated
by reference into this Form 10-K.

ITEM 7.  MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS
         OF OPERATION

     See "Management's Discussion and Analysis" on pages 30 through 39 of the
2003 Annual Report to Shareholders. That portion of the Annual Report is
incorporated by reference into this Form 10-K.

ITEM 7A. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

     See "Interest Rate Risk" section of "Management's Discussion and Analysis"
on pages 38 and 39 of the 2003 Annual Report to Shareholders. That portion of
the Annual Report is incorporated by reference into this Form 10-K.

ITEM 8.  FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

     See "Consolidated Balance Sheets" on page 10, "Consolidated Statements of
Income" on page 11, "Consolidated Statements of Changes in Shareholders Equity"
on page 12, "Consolidated Statements of Cash Flows" on page 13, and "Notes to
Consolidated Financial Statements" on pages 14-28. "Responsibility for Financial
Statements" and "Report of Independent Auditors" can be found on page 29. Those
portions of the Annual Report are incorporated by reference into this Form 10-K.

     Statistical disclosure by the Corporation includes the following
information:

     1. "Volume/Rate Analysis," on page 32.

     2. "Loan Portfolio," on page 34.

     3. "Allowance for Loan Losses," on page 35.

     4. "Under-Performing Loans," on page 36.

     5. "Deposits," on page 37.

     6. "Short-Term Borrowings," on page 37.

     7. "Consolidated Balance Sheet-Average Balances and Interest Rates," on
        page 40.

ITEM 9.  CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND
         FINANCIAL DISCLOSURE

     None

ITEM 9A  CONTROLS AND PROCEDURES

EVALUATION OF DISCLOSURE CONTROLS AND PROCEDURES

     As of the end of the period covered by this report, we carried out an
evaluation (the "Evaluation"), under the supervision and with the participation
of our President and Chief Executive Officer ("CEO") and Chief Financial Officer
("CFO"), of the effectiveness of the design and operation of our disclosure
controls and procedures ("Disclosure Controls"). Based on the Evaluation, our
CEO and CFO concluded that, subject to the limitations noted below, our
Disclosure Controls are effective in alerting them in a timely way to material
information required to be included in our periodic SEC reports.

CHANGES IN INTERNAL CONTROLS

     We have also evaluated our internal controls for financial reporting, and
there have been no significant changes in our internal controls subsequent to
the date of their last evaluation.


                                       3
<PAGE>
LIMITATIONS ON THE EFFECTIVENESS OF CONTROLS

     A control system, no matter how well conceived and operated, can provide
only reasonable, not absolute, assurance that the objectives of the control
system are met. Further, the design of a control system must reflect the fact
that there are resource constraints, and the benefits of controls must be
considered relative to their costs. Because of the inherent limitations in all
control systems, no evaluation of controls can provide absolute assurance that
all control issues and instances of fraud, if any within the Corporation, have
been detected. These inherent limitations include the realities that judgements
in decision-making can be faulty, and that breakdowns can occur because of
simple error or mistake. Additionally, controls can be circumvented by the
individual acts of some persons, by collusion of two or more people, or by
management override of the control.

     The design of any system of controls also is based in part upon certain
assumptions about the likelihood of future events, and there can only be
reasonable assurance that any design will succeed in achieving its stated goals
under all potential future conditions; over time, control may become inadequate
because of changes in conditions, or the degree of compliance with the policies
or procedures may deteriorate. Because of the inherent limitations in a
cost-effective control system, misstatements due to error or fraud may occur and
may not be detected.

                                    PART III

ITEM 10. DIRECTORS AND EXECUTIVE OFFICERS OF REGISTRANT

     In accordance with the provisions of General Instruction G to Form 10-K,
the information required for the remainder of the required disclosures under
Item 10 is not set forth herein because the Corporation intends to file with the
Securities and Exchange Commission a definitive Proxy Statement pursuant to
Regulation 14A not later than 120 days following the end of its 2003 fiscal
year, which Proxy Statement will contain such information. The information
required by Item 10 is incorporated by reference to such Proxy Statement.

ITEM 11. EXECUTIVE COMPENSATION

     In accordance with the provisions of General Instruction G to Form 10-K,
the information required for the remainder of the required disclosures under
Item 11 is not set forth herein because the Corporation intends to file with the
Securities and Exchange Commission a definitive Proxy Statement pursuant to
Regulation 14A not later than 120 days following the end of its 2003 fiscal
year, which Proxy Statement will contain such information. The information
required by Item 11 is incorporated by reference to such Proxy Statement.

ITEM 12. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

     In accordance with the provisions of General Instruction G to Form 10-K,
the information required for the remainder of the required disclosures under
Item 12 is not set forth herein because the Corporation intends to file with the
Securities and Exchange Commission a definitive Proxy Statement pursuant to
Regulation 14A not later than 120 days following the end of its 2003 fiscal
year, which Proxy Statement will contain such information. The information
required by Item 12 is incorporated by reference to such Proxy Statement.

ITEM 13. CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS

     In accordance with the provisions of General Instruction G to Form 10-K,
the information required for the remainder of the required disclosures under
Item 13 is not set forth herein because the Corporation intends to file with the
Securities and Exchange Commission a definitive Proxy Statement pursuant to
Regulation 14A not later than 120 days following the end of its 2003 fiscal
year, which Proxy Statement will contain such information. The information
required by Item 13 is incorporated by reference to such Proxy Statement.

ITEM 14. PRINCIPAL ACCOUNTANT FEES AND SERVICES

     In accordance with the provisions of General Instruction G to Form 10-K,
the information required for the remainder of the required disclosures under
Item 14 is not set forth herein because the Corporation intends to file with the
Securities and Exchange Commission a definitive Proxy Statement pursuant to
Regulation 14A not later than 120 days following the end of its 2003 fiscal
year, which Proxy Statement will contain such information. The information
required by Item 14 is incorporated by reference to such Proxy Statement.


                                       4
<PAGE>
                                    PART IV

ITEM 15. EXHIBITS, FINANCIAL STATEMENT SCHEDULES AND REPORTS ON FORM 8-K

     (a)       (1) The following consolidated financial statements of the
               Registrant and its subsidiaries are included in the 2003 Annual
               Report of First Financial Corporation attached:

               Consolidated Balance Sheets--December 31, 2003 and 2002

               Consolidated Statements of Income--Years ended December 31, 2003,
               2002, and 2001

               Consolidated Statements of Changes in Shareholders' Equity--Years
               ended December 31, 2003, 2002, and 2001

               Consolidated Statements of Cash Flows--Years ended December 31,
               2003, 2002, and 2001 Notes to Consolidated Financial Statements

         (2)   Schedules to the Consolidated Financial Statements required by
               Article 9 of Regulation S-X are not required, inapplicable, or
               the required information has been disclosed elsewhere.

         (3)   Listing of Exhibits:

               Exhibit Number          Description
               --------------          -----------

                    13                 Annual Report

                    21                 Subsidiaries

                    31.1               Certification for Annual Report of
                                       Form 10-K by Principal Executive Officer

                    31.2               Certification for Annual Report of Form
                                       10-K by Principal Financial Officer

                    32.1               Certification of Principal Executive
                                       Officer pursuant to Section 906 of the
                                       Sarbanes-Oxley Act of 2002

                    32.2               Certification of Principal Financial
                                       Officer pursuant to Section 906 of the
                                       Sarbanes-Oxley Act of 2002

     (b) Reports on Forms 8-K--First Financial furnished a Form 8-K to the
Securities and Exchange Commission on November 3, 2003 in connection with the
announcement of its earnings for the third quarter of 2003 and on November 21,
2003 in connection with the announcement of its declaration of a semi-annual
dividend.

     (c) Exhibits--Exhibits to (a)(3) listed above are attached to this report.

     (d) Financial Statements Schedules--No schedules are required to be
submitted. See response to ITEM 15(a)(2).


                                       5

<PAGE>
                                   SIGNATURES

Pursuant to the requirements of Section 13 or 15 (d) of the Securities Exchange
Act of 1934, the registrant has duly caused this report to be signed on its
behalf by the undersigned, thereunto duly authorized.

First Financial Corporation


                                             Michael A. Carty, Signed
                                             ----------------------------------
                                             Michael A. Carty, Treasurer
                                             (Principal Financial Officer
                                             and Principal Accounting Officer)
                                             Date: February 17, 2004

Pursuant to the requirements of the Securities Exchange Act of 1934, this report
has been signed below by the following persons on behalf of the registrant and
in the capacities and on the dates indicated.


<TABLE>
<CAPTION>
Name                                                    Date
<S>                                                     <C>
Donald E. Smith, Signed                                 February 17, 2004
-----------------------                                 -----------------
Donald E. Smith, President & Director


Michael A. Carty, Signed                                February 17, 2004
------------------------                                -----------------
Michael A. Carty, Treasurer
(Principal Financial Officer
and Principal Accounting Officer)


B. Guille Cox, Jr., Signed                              February 17, 2004
--------------------------                              -----------------
B. Guille Cox, Jr., Director


Thomas T. Dinkel, Signed                                February 17, 2004
------------------------                                -----------------
Thomas T. Dinkel, Director


Anton H. George, Signed                                 February 17, 2004
-----------------------                                 -----------------
Anton H. George, Director


Mari H. George, Signed                                  February 17, 2004
----------------------                                  -----------------
Mari H. George, Director


Gregory L. Gibson, Signed                               February 17, 2004
-------------------------                               -----------------
Gregory L. Gibson, Director


Norman L. Lowery, Signed                                February 17, 2004
------------------------                                -----------------
Norman L. Lowery, Director
(Principal Executive Officer)


William A. Niemeyer, Signed                             February 17, 2004
---------------------------                             -----------------
William A. Niemeyer, Director


Patrick O'Leary, Signed                                 February 17, 2004
-----------------------                                 -----------------
Patrick O'Leary, Director


----------------------------
Chapman J. Root II, Director                            February 17, 2004
                                                        -----------------


Virginia L. Smith, Signed
-------------------------
Virginia L. Smith, Director                             February 17, 2004
                                                        -----------------


</TABLE>


                                       6