<PAGE>

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                FORM 10-K/A No. 1

 [X]   Annual Report Pursuant to Section 13 or 15(d) of the Securities Exchange
       Act of 1934 For the fiscal year ended December 31, 2001

                                       OR

 [_]   Transition Report Pursuant to Section 13 or 15(d) of the Securities
       Exchange Act of 1934.

                        Commission file number 001-12617

                             Trigon Healthcare, Inc.
             (Exact name of registrant as specified in its charter)
          Virginia                                              54-1773225
 (State or other jurisdiction of                             (I.R.S. Employer
  incorporation or organization)                            Identification No.)

                   2015 Staples Mill Road, Richmond, VA 23230
                    (Address of principal executive offices)

        Registrant's telephone number, including area code (804) 354-7000

Securities registered pursuant to Section 12(b) of the Act:
   Class A Common Stock, $.01 Par Value                  New York Stock Exchange
         (Title of Class)                                   (Name of 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 or 15(d) of the Securities Exchange Act of 1934 during
the preceding 12 months (or for such shorter period that the registrant was
required to file such reports), and (2) has been subject to such filing
requirements for the past 90 days. [X] Yes [_] 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 or any amendment to this
Form 10-K. [_]

The aggregate market value of the voting stock held by non-affiliates of the
registrant as of April 25, 2002 was approximately $2,938,762,000 (based on the
last reported sales price of $82.12 per share on April 25, 2002, on the New York
Stock Exchange).

As of April 25, 2002, 35,786,194 shares of the registrant's Class A Common
Stock, par value $.01 per share, were issued and outstanding.

                      DOCUMENTS INCORPORATED BY REFERENCE:
Certain portions of Trigon Healthcare Inc.'s Annual Report to Shareholders for
the year ended December 31, 2001 into Parts II and IV of this Form 10-K.
Certain portions of Trigon Healthcare Inc.'s definitive Proxy Statement dated
March 22, 2002 for the Annual Meeting of Shareholders into Part III of this Form
10-K.

<PAGE>

The exhibits to this Form 10-K/A No. 1 are amended to include the 2001 annual
reports for the Trigon Healthcare, Inc. Employee Stock Purchase Plan and the
Trigon Insurance Company 401(k) Restoration Plan, Consents of Independent
Auditors and the Amendment to the Trigon Healthcare, Inc. Non-Employee Director
Stock Incentive Plan. There are no other differences.

PART I

ITEM 1.  BUSINESS
Omitted.

ITEM 2.  PROPERTIES
Omitted.

ITEM 3.  LEGAL PROCEEDINGS
Omitted.

ITEM 4.  SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS
Not applicable.

PART II

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

ITEM 6.  SELECTED FINANCIAL DATA
Omitted.

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

ITEM 7A.  QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK
Omitted.

ITEM 8.  FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA
Omitted.

ITEM 9.  CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND
FINANCIAL DISCLOSURE
Not applicable.

PART III

ITEM 10.  DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT
Omitted.

ITEM 11.  EXECUTIVE COMPENSATION
Omitted.

ITEM 12.  SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT
Omitted.

ITEM 13.  CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS
Omitted.

<PAGE>

PART IV

ITEM 14. EXHIBITS, FINANCIAL STATEMENT SCHEDULES, AND REPORTS ON FORM 8-K
(a) The following documents are filed as part of this report.

    1.   Consolidated Financial Statements from the Company's 2001 Annual Report
         to Shareholders are incorporated herein by reference in Item 8:
         Omitted.

    2.   Financial statement schedules
         Omitted.

    3.   Exhibits.  The following is a list of exhibits to this Form 10-K.

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

    2     --  Amended and Restated Plan of Demutualization (incorporated by
              reference to exhibits filed with the Company's Registration
              Statement on Form S-1 (registration number 333-09773)).
  3.1     --  Amended and Restated Articles of Incorporation of Trigon
              Healthcare, Inc. (incorporated by reference to exhibits filed with
              the Company's Registration Statement on Form S-1 (registration
              number 333-09773)).
  3.2     --  Amended and Restated Bylaws of Trigon Healthcare, Inc. dated April
              28, 1999 (incorporated by reference to exhibits filed with the
              Company's Form 10-Q for the period ended March 31, 1999).
  3.3     --  Articles of Amendment to Amended and Restated Articles of
              Incorporation setting forth the designation, preferences and
              rights of Series A Junior Participating Preferred Stock of Trigon
              Healthcare, Inc. dated July 16, 1997 (Incorporated by reference to
              exhibits filed with the Company's Form 8-A/A filed on July 16,
              1997).
    4     --  Form of Stock Certificate (other Instruments Defining the Rights
              of Security-Holders) (incorporated by reference to exhibits filed
              with the Company's Registration Statement on Form S-1(registration
              number 333-09773)).
  4.1     --  Rights Agreement dated as of July 16, 1997 between Trigon
              Healthcare, Inc. and First Chicago Trust Company of New York, as
              Rights Agent (incorporated by reference to exhibits filed with the
              Company's Form 8-A/A filed on July 16, 1997).
  4.2     --  Form of Rights Certificate (incorporated by reference to exhibits
              filed with the Company's Form 8-A/A filed on July 16, 1997).
 10.1     --  License Agreement by and between the Blue Cross and Blue Shield
              Association and the Company (incorporated by reference to exhibits
              filed with the Company's Form 10-K for the year ended December 31,
              1996).
                  (a) Blue Cross license
                  (b) Blue Shield license
 10.2     --  Limited Fixed Return Plan for Certain Officers and Directors of
              Trigon Insurance Company (incorporated by reference to exhibits
              filed with the Company's Registration Statement on Form S-1
              (registration number 333-09773)). *
 10.4     --  Non-Contributory Retirement Program for Certain Employees of
              Trigon Insurance Company (incorporated by reference to exhibits
              filed with the Company's Registration Statement on Form S-1
              (registration number 333-09773)). *
 10.5     --  Amended and Restated Supplemental Executive Retirement Program
              for Certain Employees of Trigon Insurance Company dated as of
              October 1, 1998 (incorporated by reference to exhibits filed with
              the Company's Form 10-K for the year ended December 31, 1998). *
 10.6     --  Salary Deferral Plan for Norwood H. Davis, Jr. (incorporated by
              reference to exhibits filed with the Company's Registration
              Statement on Form S-1 (registration number 333-09773)). *
 10.7     --  Amended and Restated Employment Agreement dated September 16, 1998
              by and between Trigon Insurance Company and Norwood H. Davis, Jr.
              (incorporated by reference to exhibits filed with the Company's
              Form 10-Q for the period ended September 30, 1998). *

<PAGE>

  10.9    --  Amended and Restated Employees' Thrift Plan of Trigon Insurance
              Company dated as of October 1, 1998 (incorporated by reference to
              exhibits filed with the Company's Form 10-K for the year ended
              December 31, 1998). *
  10.10   --  Amended and Restated Trigon Insurance Company 401(k) Restoration
              Plan dated as of October 1, 1998 (Incorporated by reference to
              exhibits filed with the Company's Form 10-K for the year ended
              December 31, 1998). *
  10.12   --  Form of Employment Agreement dated as of December 12, 1990 by and
              between Trigon Insurance Company and John C. Berry and certain
              other executive officers (incorporated by reference to exhibits
              filed with the Company's Registration Statement on Form S-1
              (registration number 333-09773)). *
  10.15   --  1997 Stock Incentive Plan (incorporated by reference to exhibits
              filed with the Company's Proxy Statement dated March 13, 1997). *
  10.16   --  Employee Stock Purchase Plan (incorporated by reference to
              exhibits filed with the Company's Proxy Statement dated March 13,
              1997). *
  10.17   --  Non-Employee Directors Stock Incentive Plan (incorporated by
              reference to exhibits filed with the Company's Proxy Statement
              dated March 13, 1997). *
  10.18   --  Amendment to the License Agreement by and between the Blue Cross
              and Blue Shield Association and the Company (incorporated by
              reference to exhibits filed with the Company's Form 10-Q for the
              period ended September 30, 1997).
  10.19   --  Amendment to the Non-Contributory Retirement Program for Certain
              Employees of Trigon Insurance Company (incorporated by reference
              to exhibits filed with the Company's Form 10-K for the year ended
              December 31, 1997). *
  10.20   --  Form of Executive Continuity Agreement dated as of September 16,
              1998 between Trigon Insurance Company and Thomas G. Snead, Jr. and
              certain other executive officers (incorporated by reference to
              exhibits filed with the Company's Form 10-Q for the period ended
              September 30, 1998). *
  10.21   --  Form of Executive Continuity Agreement dated as of September 16,
              1998 between Trigon Insurance Company and John C. Berry and
              certain other executive officers (incorporated by reference to
              exhibits filed with the Company's Form 10-Q for the period ended
              September 30, 1998). *
  10.22   --  Amendment to the Non-Contributory Retirement Program for
              Certain Employees of Trigon Insurance Company (now to be known as)
              The Trigon Insurance Company Retirement Program dated as of
              October 1, 1998 (incorporated by reference to exhibits filed with
              the Company's Form 10-K for the year ended December 31, 1998).*
  10.23   --  Clarifying Amendment to the Non-Contributory Retirement Program
              for Certain Employees of Trigon Insurance Company (now to be known
              as) The Trigon Insurance Company Retirement Program dated as of
              October 1, 1998 (incorporated by reference to exhibits filed with
              the Company's Form 10-K for the year ended December 31, 1998). *
  10.24   --  Thomas G. Snead Employment Agreement dated May 19, 1999
              (incorporated by reference to exhibits filed with the Company's
              Form 10-Q for the period ended June 30, 1999). *
  10.25   --  Amendment No. 1 to Executive Continuity Agreement Between Trigon
              Insurance Company and Thomas G. Snead, Jr. dated May 19, 1999
              (incorporated by reference to exhibits filed with the Company's
              Form 10-Q for the period ended June 30, 1999).*
  10.26   --  Clarifying Amendment No. 2 to the Non-Contributory Retirement
              Program for Certain Employees of Trigon Insurance Company (now to
              be known as) The Trigon Insurance Company Retirement Program
              (incorporated by reference to exhibits filed with the Company's
              Form 10-K for the year ended December 31, 1999). *
  10.27   --  Clarifying Amendment No. 3 to the Non-Contributory Retirement
              Program for Certain Employees of Trigon Insurance Company (now to
              be known as) The Trigon Insurance Company Retirement Program
              (incorporated by reference to exhibits filed with the Company's
              Form 10-K for the year ended December 31, 1999). *
  10.28   --  Clarifying Amendment No. 4 to The Trigon Insurance Company
              Retirement Program (incorporated by reference to exhibits filed
              with the Company's Form 10-K for the year ended December 31,
              1999). *

<PAGE>

 10.30    --  First amendment to the Trigon Healthcare, Inc. 1997 Stock
              Incentive Plan dated February 15, 2000 (incorporated by reference
              to exhibits filed with the Company's Form 10-Q for the period
              ended March 31, 2000). *
 10.32    --  Form of Executive Continuity Agreement dated as of February 12,
              2001 between Trigon Insurance Company and John W. Coyle
              (incorporated by reference to exhibits filed with the Company's
              Form 10-Q for the period ended March 31, 2001). *
 10.33    --  Form of Employment Agreement dated as of February 12, 2001 by
              and between Trigon Insurance Company and John W. Coyle
              (incorporated by reference to exhibits filed with the Company's
              Form 10-Q for the period ended March 31, 2001). *
 10.34    --  Five-Year Credit Agreement dated as of November 14, 2001 among
              Trigon Healthcare, Inc., the banks party thereto and JPMorgan
              Chase Bank, as Administrative Agent (incorporated by reference to
              exhibits filed with the Company's Form 10-K for the year ended
              December 31, 2001).
 10.35    --  364-Day Credit Agreement dated as of November 14, 2001 among
              Trigon Healthcare, Inc., the banks party thereto and JPMorgan
              Chase Bank, as Administrative Agent (incorporated by reference to
              exhibits filed with the Company's Form 10-K for the year ended
              December 31, 2001).
 10.36    --  Amendment to the Trigon Healthcare, Inc. Non-Employee Director
              Stock Incentive Plan dated April 24, 2002. *
    11    --  Computation of per share earnings. Refer to Note 14, "Net Income
              and Net Income Per Share," on page 50 of Trigon Healthcare Inc.'s
              2001 Annual Report to Shareholders, which is incorporated herein
              by reference.
    13    --  Excerpts from the Company's Annual Report to Shareholders for the
              year ended December 31, 2001 (incorporated by reference to
              exhibits filed with the Company's Form 10-K for the year ended
              December 31, 2001).
    21    --  Subsidiaries of the Registrant (incorporated by reference to
              exhibits filed with the Company's 10-K for the year ended December
              31, 2001).
  23.1    --  Independent Auditors' Consent (incorporate by reference to
              exhibits filed with the Company's 10-K for the year ended December
              31, 2001).
  23.2    --  Independent Auditors' Consent.
  23.3    --  Independent Auditors' Consent.
  99.1    --  Trigon Healthcare, Inc. Employee Stock Purchase Plan Audited
              Financial Statements as of December 31, 2001 and 2000 and for the
              three years ended December 31, 2001, 2000 and 1999.
  99.2    --  Trigon Insurance Company 401(k) Restoration Plan Audited Financial
              Statements as of December 31, 2001 and 2000 and for the three
              years ended December 31, 2001, 2000 and 1999.

 *   Management contract or compensatory plan or arrangement required to be
     filed as an exhibit to this Form 10-K pursuant to Item 14(c) of this Form
     10-K.

All other schedules for which provision is made in the applicable accounting
regulation of the Securities and Exchange Commission are not required under the
related instructions or are inapplicable, and therefore have been omitted.

<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.

                                                  TRIGON HEALTHCARE, INC.
                                                        Registrant

                                                      By:  /s/ THOMAS R. BYRD
                                                           ---------------------
                                                           THOMAS R. BYRD


                                             Title:   SENIOR VICE PRESIDENT AND
                                                      CHIEF FINANCIAL OFFICER

Date:  April 24, 2002

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>
        SIGNATURE                              TITLE                                    DATE
        ---------                              -----                                    ----

<S>                                     <C>                                         <C>
/s/ THOMAS G. SNEAD, JR.                Chairman of the Board and                   April 24, 2002
--------------------------------------  Chief Executive Officer
THOMAS G. SNEAD, JR.                    (Principal Executive Officer)




/s/ THOMAS R. BYRD                      Senior Vice President and Chief             April 24, 2002
--------------------------------------  Financial Officer (Principal Financial
THOMAS R. BYRD                          and Accounting Officer)



/s/ LENOX D. BAKER, JR.                 Director                                    April 24, 2002
--------------------------------------
LENOX D. BAKER, JR., M.D.



/s/ A. HUGH EWING, III                  Director                                    April 24, 2002
--------------------------------------
A. HUGH EWING, III



/s/ ROBERT M. FREEMAN                   Director                                    April 24, 2002
--------------------------------------
ROBERT M. FREEMAN
                                                                        </TABLE>

<PAGE>


SIGNATURE                               TITLE                    DATE
---------                               -----                    ----

/s/ GARY A. JOBSON                      Director                 April 24, 2002
--------------------------------------
GARY A. JOBSON



/s/ JOSEPH S. MALLORY                   Director                 April 24, 2002
--------------------------------------
JOSEPH S. MALLORY



/s/ DONALD B. NOLAN                     Director                 April 24, 2002
--------------------------------------
DONALD B. NOLAN, M.D.



/s/ WILLIAM N. POWELL                   Director                 April 24, 2002
--------------------------------------
WILLIAM N. POWELL



/s/ JOHN SHERMAN, JR.                   Director                 April 24, 2002
--------------------------------------
JOHN SHERMAN, JR.



/s/ R. GORDON SMITH                     Director                 April 24, 2002
--------------------------------------
R. GORDON SMITH, ESQ.



/s/ JACKIE M. WARD                      Director                 April 24, 2002
--------------------------------------
JACKIE M. WARD




<PAGE>

EXHIBIT INDEX

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

10.36     --  Amendment to the Trigon Healthcare, Inc. Non-Employee Director
              Stock Incentive Plan dated April 24, 2002.
23.2      --  Consent of Independent Auditors.
23.3      --  Consent of Independent Auditors.
99.1      --  Trigon Healthcare, Inc. Employee Stock Purchase Plan Audited
              Financial Statements as of December 31, 2001 and 2000 and for the
              three years ended December 31, 2001, 2000 and 1999.
99.2      --  Trigon Insurance Company 401(k) Restoration Plan Audited Financial
              Statements as of December 31, 2001 and 2000 and for the three
              years ended December 31, 2001, 2000 and 1999.