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                                                                   EXHIBIT 10.28

                                 THIRD AMENDMENT
                                       TO
                             RISK SHARING AGREEMENT
                                 BY AND BETWEEN
                ALLEGHENY HEALTH, EDUCATION & RESEARCH FOUNDATION
                                       AND
                              COVENTRY CORPORATION
                          ON BEHALF OF MEMBER COMPANIES

THIS AGREEMENT is executed the 25th day of August 1997, by and between
HealthAmerica Pennsylvania, Inc., a Pennsylvania corporation licensed to operate
a health maintenance organization ("HealthAmerica"), Coventry Corporation, a
Delaware corporation ("Coventry") for and on behalf of the Member Companies (as
hereinafter defined) other than HealthAmerica, and Allegheny Health, Education
and Research Foundation, a Pennsylvania nonprofit corporation ("AHERF").

WHEREAS, HealthAmerica and Coventry entered into a Risk Sharing Agreement with
AHERF on March 31, 1997; and

WHEREAS, on June 11, 1997 HealthAmerica and Coventry entered into a First
Amendment to Risk Sharing Agreement with AHERF; and

WHEREAS, on June 30, 1997 HealthAmerica and Coventry and Coventry Health Plan of
West Virginia, Inc. d/b/a HealthAssurance HMO entered into a Second Amendment to
Risk Sharing Agreement with AHERF; and

WHEREAS, the parties to said Agreement desire to further amend said Agreement to
incorporate additional compliance language in order to comport with certain
regulatory requirements of the state of West Virginia.

NOW, THEREFORE, in consideration of the mutual covenants, premises and
undertakings herein and intending to be legally bound hereby, the parties agree
as follows:

 1. Incorporation of Amendments. To the extent not modified by this Third 
    Amendment, the Second Amendment, First Amendment and Risk Sharing Agreement
    are incorporated herein by reference.

 2. Section 3, Duties of AHERF, shall be expanded, specifically for purposes of
    compliance with West Virginia Code Section 114-43-1 et seq, as it relates
    to West Virginia HMO, to add the following terms and conditions:

                   3.1.11 AHERF shall adhere to all quality and accessibility
                      standards to which West Virginia HMO is subject. Further,
                      to the extent AHERF subcontracts for the provision of
                      health care services it is agreed that all subcontractors
                      must adhere


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                      to the quality and accessibility standards to which West
                      Virginia HMO is subject.
                  
                  3.1.12 AHERF shall maintain records which are adequate to
                      clearly differentiate the transactions which relate to the
                      provision of health care services on behalf of West
                      Virginia HMO.

                  3.1.13 AHERF and any Contracted Providers with which it
                      contracts for the provision of health care services shall
                      obtain and provide to West Virginia HMO no later than the
                      first day of June of each year an annual audited financial
                      report prepared by an independent certified public
                      accountant.

                  3.1.14 AHERF will only provide services on behalf of West
                      Virginia HMO in counties where West Virginia HMO is
                      authorized to operate by the West Virginia Department of
                      Insurance.

                  3.1.15 AHERF shall maintain working capital in the form of
                      cash or equivalent liquid assets at least equal to one
                      month's claims calculated by using the monthly average of
                      actual and estimated claims for the prior six months for
                      all health services provided under the Agreement.

                  3.1.16 AHERF shall create a segregated fund, which may be
                      aggregated, equal to the entire monthly IBNR as of the
                      first day of each month as actuarially determined by West
                      Virginia HMO.

3.   Section 4 DUTIES OF HEALTHAMERICA/WEST VIRGINIA HMO, shall be expanded,
     specifically for purposes of compliance with West Virginia Code Section
     114-43-1 et. seq., as it relates to West Virginia HMO, to add the following
     terms and conditions:

                  4.1.10 West Virginia HMO shall be responsible for maintaining
     appropriate levels of capital, surplus, claims reserves and other financial
     criteria as established pursuant to statute or rule.

                  4.1.11 All Covered Individuals or Covered Individual group 
     contracts will be entered into directly with West Virginia HMO and 
     specifically not with AHERF.

4.   Section 5.9, NO BALANCE BILLING, shall be amended to read in its entirety
     as follows:

                  "AHERF hereby agrees, on behalf of itself and its Affiliated
                  and Contracted Providers, that in no event, including but not
                  limited to, non-payment by a Member Company, a Member Company
                  insolvency or breach of the Agreement, shall AHERF bill,
                  charge or collect a deposit from, seek compensation,
                  remuneration or reimbursement from, or have any recourse
                  against, Covered Individuals or persons other than a Member
                  Company acting on their behalf for Covered Services. This
                  Section shall not prohibit collection of Copayments,
                  Coinsurance, Deductibles or Financial Penalties made in


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                  accordance with the terms of the applicable Covered
                  Individual's contract with a Member Company nor billing for
                  non-Covered Service for which Covered Individuals have had
                  prior notification and approved.

                  "AHERF further agrees that: (i) the no balance billing
                  provision herein shall survive the termination of the
                  Agreement regardless of the cause giving rise to termination
                  and shall be construed to be for the benefit of Covered
                  Individuals; and (ii) this no balance billing provision
                  supersedes any oral or written contrary Agreement now existing
                  or hereafter entered between AHERF and a Covered Individual or
                  a person acting on his/her behalf.

                  "Any modification, addition or deletion to the provisions of
                  this Section shall become effective on a date no earlier that
                  sixty (60) days after the Pennsylvania Secretary of Health and
                  the requisite governmental body of the State of Ohio and the
                  State of West Virginia, have received written notice of such
                  proposed change."

5. Section 5.11 of the Risk Sharing Agreement is intentionally deleted for
   purposes of West Virginia HMO.

6. Section 22, GOVERNING LAW, shall be amended to read in its entirety as
   follows:

                  "This Agreement shall be governed by the laws of the
                  Commonwealth of Pennsylvania as it in any way pertains to
                  HealthAmerica Pennsylvania, Inc., the State of Ohio as it in
                  any way pertains to HealthAmerica Pennsylvania, Inc. d/b/a
                  HealthAssurance HMO, and the State of West Virginia as the
                  Agreement in any way pertains to Coventry Health Plan of West
                  Virginia, Inc. Any actions, lawsuit or claim brought by either
                  party pertaining to breach, reformation or interpretation of
                  this Agreement as it relates to HealthAmerica Pennsylvania,
                  Inc. shall be exclusively brought in Pittsburgh,
                  Pennsylvania."

7. EFFECTIVE DATE. The effective date of this Agreement for purposes of West 
   Virginia HMO shall be July 1, 1997.

8. ALL OTHER TERMS. Notwithstanding anything contained herein, all other terms
   of the Agreement and the First and Second Amendments shall remain unaltered
   and in full force and effect.


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IN WITNESS WHEREOF, the undersigned have executed this Agreement as of the day
and year first above written.


Allegheny Health, Education          HealthAmerica Pennsylvania, Inc.
& Research Foundation


/s/ David W. McConnell               /s/ ROBERT A. MAYER
---------------------------          ------------------------------------------
David W. McConnell                   Robert A. Mayer
Executive Vice President and         President and Chief Executive Officer
  Chief Financial Officer



                                     Coventry Corporation


                                     /s/ ROBERT A. MAYER
                                     -----------------------------------------
                                     Robert A. Mayer
                                     Senior Vice President



                                     HealthAmerica Pennsylvania, Inc. d/b/a
                                     HealthAssurance HMO

                                     /s/ ROBERT A. MAYER
                                     ------------------------------------------
                                     By: Robert A. Mayer
                                         --------------------------------------
                                     Title: President and Chief Executive 
                                            Officer
                                           ------------------------------------


                                     Coventry Health Plan of West Virginia, Inc.

                                     /s/ ROBERT A. MAYER
                                     ------------------------------------------
                                     By: Robert A. Mayer
                                         --------------------------------------
                                     Title: President and Chief Executive 
                                            Officer
                                            -----------------------------------