<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, 2000

                                       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
<TABLE>
<S>                                                               <C>
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)
</TABLE>

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, 2001 was approximately $2,075,409,000 (based on the
last reported sales price of $56.80 per share on April 25, 2001, on the New York
Stock Exchange).

As of April 25, 2001, 36,538,894 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, 2000 into Parts II and IV of this Form 10-K.
Certain portions of Trigon Healthcare Inc.'s definitive Proxy Statement dated
March 23, 2001 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 2000 annual
reports for the Trigon Healthcare, Inc. Employee Stock Purchase Plan and the
Trigon Insurance Company 401(k) Restoration Plan and Consents of Independent
Auditors. 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 Trigon Healthcare Inc.'s 2000
        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)). *
 10.14  -- Credit Agreement dated as of February 5, 1997 among Trigon
            Healthcare, Inc., the banks party thereto and Morgan Guaranty Trust
            Company of New York, as Agent (incorporated by reference to exhibits
            filed with the Company's Form 10-K for the year ended December 31,
            1996).
 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). *
<PAGE>

 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). *
 10.29  -- Amendment No. 1 dated December 14, 1999 to the Credit Agreement dated
            as of February 5, 1997 among Trigon Healthcare, Inc., the banks
            party thereto and Morgan Guaranty Trust Company of New York, as
            Agent (incorporated by reference to exhibits filed with the
            Company's Form 10-K for the year ended December 31, 1999).
 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). *
 10.31  -- Amendment No. 2 dated March 24, 2000 to the Credit Agreement dated as
            of February 5, 1997 among Trigon Healthcare, Inc., the banks party
            thereto and Morgan Guaranty Trust Company of New York, as Agent
            (incorporated by reference to exhibits filed with the Company's Form
            10-K for the year ended December 31, 2000).
    11  -- Computation of per share earnings. Refer to Note 15, "Net Income and
            Net Income Per Share," on page 48 of Trigon Healthcare Inc.'s 2000
            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, 2000 (incorporated by reference to exhibits
            filed with the Company's 10-K for the year ended December 31, 2000).
    21  -- Subsidiaries of the Registrant (incorporated by reference to exhibits
            filed with the Company's 10-K for the year ended December 31, 2000).
  23.1  -- Consent of KPMG LLP (incorporated by reference to exhibits filed with
            the Company's 10-K for the year ended December 31, 2000).
  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, 2000 and 1999 and for the
            three years ended December 31, 2000, 1999 and 1998.
  99.2  -- Trigon Insurance Company 401(k) Restoration Plan Audited Financial
            Statements as of December 31, 2000 and 1999 and for the three years
            ended December 31, 2000, 1999 and 1998.

*  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 25, 2001

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
-----------------------------------
THOMAS G. SNEAD, JR.                                  Chief Executive Officer
                                                      (Principal Executive Officer)                               April 25, 2001



/s/ THOMAS R. BYRD                                    Senior Vice President and Chief
-----------------------------------
THOMAS R. BYRD                                         Financial Officer  (Principal Financial
                                                       and Accounting Officer)                                    April 25, 2001


/s/ A. HUGH EWING, III                                Director                                                    April 25, 2001
-----------------------------------
A. HUGH EWING, III



/s/ LENOX D. BAKER, JR.                               Director                                                    April 25, 2001
-----------------------------------
LENOX D. BAKER, JR., M.D.



/s/ ROBERT M. FREEMAN                                 Director                                                    April 25, 2001
-----------------------------------
ROBERT M. FREEMAN



/s/ GARY A. JOBSON                                    Director                                                    April 25, 2001
-----------------------------------
GARY A. JOBSON
</TABLE>
<PAGE>

<TABLE>
<CAPTION>
SIGNATURE                                             TITLE                                DATE
---------                                             -----                                ----
<S>                                              <C>                                  <C>


/s/ JOSEPH S. MALLORY                                 Director                             April 25, 2001
--------------------------------------
JOSEPH S. MALLORY



/s/ DONALD B. NOLAN                                   Director                             April 25, 2001
--------------------------------------
DONALD B. NOLAN, M.D.



/s/ WILLIAM N. POWELL                                 Director                             April 25, 2001
--------------------------------------
WILLIAM N. POWELL



/s/ JOHN SHERMAN, JR.                                 Director                             April 25, 2001
--------------------------------------
JOHN SHERMAN, JR.



/s/ R. GORDON SMITH                                   Director                             April 25, 2001
--------------------------------------
R. GORDON SMITH, ESQ.



/s/ HUBERT R. STALLARD                                Director                             April 25, 2001
--------------------------------------
HUBERT R. STALLARD
</TABLE>
<PAGE>

EXHIBIT INDEX

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

 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, 2000 and 1999 and for the three years
          ended December 31, 2000, 1999 and 1998.

 99.2 -- Trigon Insurance Company 401(k) Restoration Plan Audited Financial
          Statements as of December 31, 2000 and 1999 and for the three years
          ended December 31, 2000, 1999 and 1998.