Joint Filing Agreement

                                                                       EXHIBIT 4

                             Joint Filing Agreement

     The undersigned hereby agree that the statement on Schedule 13D with
respect to the shares of Common Stock of Coventry Health Care, Inc. is, and any
amendment thereto signed by each of the undersigned shall be, filed on behalf of
each undersigned pursuant to and in accordance with the provisions of 13d-1(k)
under the Securities Exchange Act of 1934, as amended.


Dated: May 11, 2000                     WARBURG, ▇▇▇▇▇▇ VENTURES, L.P.

                                        By: Warburg, ▇▇▇▇▇▇ & Co.,
                                            General Partner

                                        By: /s/ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇▇
                                            ------------------------------
                                            Partner


Dated: May 11, 2000                     WARBURG, ▇▇▇▇▇▇ & CO.

                                        By: /s/ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇▇
                                            ------------------------------
                                            Partner


Dated: May 11, 2000                     ▇.▇. ▇▇▇▇▇▇▇, ▇▇▇▇▇▇ & CO., LLC

                                        By: Warburg, ▇▇▇▇▇▇ & Co.,
                                            General Partner

                                        By: /s/ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇▇
                                            ------------------------------
                                            Partner


Dated: May 11, 2000                     WARBURG, ▇▇▇▇▇▇ EQUITY PARTNERS, L.P.

                                        By: Warburg, ▇▇▇▇▇▇ & Co.,
                                            General Partner

                                        By: /s/ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇▇
                                            ------------------------------
                                            Partner

Dated: May 11, 2000                     By: /s/ ▇▇▇▇ ▇▇▇▇▇▇▇▇
                                            ------------------------------
                                            Name: ▇▇▇▇ ▇▇▇▇▇▇▇▇
                                                  Trustee


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Dated: May 11, 2000                     By: /s/ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇▇
                                            ------------------------------
                                            Name: ▇▇▇▇▇▇▇ ▇▇▇▇▇▇▇
                                                  Trustee


Dated: May 11, 2000                     By: /s/ ▇▇▇▇▇▇▇▇ ▇▇▇▇
                                            ------------------------------
                                            Name: ▇▇▇▇▇▇▇▇ ▇▇▇▇
                                                  Trustee


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