<PAGE>


                                                             EXHIBIT 10.20



                                JOINDER AGREEMENT

                  THIS JOINDER AGREEMENT (the "Agreement"), dated as of June 30,
2004, is by and between IASIS FINANCE TEXAS HOLDINGS, LLC, a Delaware limited
liability company (the "Subsidiary"), and BANK OF AMERICA, N.A., in its capacity
as Administrative Agent under that certain Amended and Restated Credit Agreement
(as it may be amended, modified, restated or supplemented from time to time, the
"Credit Agreement"), dated as of June 22, 2004, by and among IASIS HEALTHCARE
LLC, a Delaware limited liability company (the "Borrower"), the Guarantors, the
Lenders and Bank of America, N.A., as Administrative Agent, Swingline Lender and
L/C Issuer. All of the defined terms in the Credit Agreement are incorporated
herein by reference.

                  The Loan Parties are required by Section 7.11 of the Credit
Agreement to cause the Subsidiary to become a "Guarantor".

                  Accordingly, the Subsidiary hereby agrees as follows with the
Administrative Agent, for the benefit of the Lenders:

                  1. The Subsidiary hereby acknowledges, agrees and confirms
that, by its execution of this Agreement, the Subsidiary will be deemed to be a
party to the Credit Agreement and a "Guarantor" for all purposes of the Credit
Agreement, and shall have all of the obligations of a Guarantor thereunder as if
it had executed the Credit Agreement. The Subsidiary hereby ratifies, as of the
date hereof, and agrees to be bound by, all of the terms, provisions and
conditions applicable to the Guarantors contained in the Credit Agreement.
Without limiting the generality of the foregoing terms of this paragraph 1, the
Subsidiary hereby jointly and severally together with the other Guarantors,
guarantees to each Lender and the Administrative Agent, as provided in Article
IV of the Credit Agreement, the prompt payment and performance of the
Obligations in full when due (whether at stated maturity, as a mandatory
prepayment, by acceleration or otherwise) strictly in accordance with the terms
thereof.

                  2. The Subsidiary hereby acknowledges, agrees and confirms
that, by its execution of this Agreement, the Subsidiary will be deemed to be a
party to the Security Agreement and shall have all the obligations of an
"Obligor" (as such term is defined in the Security Agreement) thereunder as if
it had executed the Security Agreement. The Subsidiary hereby ratifies, as of
the date hereof, and agrees to be bound by, all of the terms, provisions and
conditions contained in the Security Agreement. Without limiting the generality
of the foregoing terms of this paragraph 2, the Subsidiary hereby grants to the
Administrative Agent, for the benefit of the Lenders, a continuing security
interest in, and a right of set off against, any and all right, title and
interest of the Subsidiary in and to the Collateral (as such term is defined in
Section 2 of the Security Agreement) of the Subsidiary. The Subsidiary hereby
represents and warrants to the Agent that:

<PAGE>


                  (i) The Subsidiary's chief executive office and chief place of
         business are (and for the prior four months have been) located at the
         locations set forth on Schedule 1 attached hereto and the Subsidiary
         keeps its books and records at such locations.

                  (ii) The type of Collateral owned by the Subsidiary and the
         location of all Collateral owned by the Subsidiary is as shown on
         Schedule 2 attached hereto.

                  (iii) The Subsidiary's legal name is as shown in this
         Agreement and the Subsidiary has not in the past four months changed
         its name, been party to a merger, consolidation or other change in
         structure or used any tradename except as set forth in Schedule 3
         attached hereto.

                  (iv) The patents and trademarks listed on Schedule 4 attached
         hereto constitute all of the registrations and applications for the
         patents and trademarks owned by the Subsidiary.

                  (v) The Subsidiary Equity (as such term is defined in Section
         1 of the Security Agreement) owned by the Subsidiary is listed on
         Schedule 5 attached hereto.

                  3. The address of the Subsidiary for purposes of all notices
and other communications is 117 Seaboard Lane, Building E, Franklin, TN 37067,
Attention of President or General Counsel of IASIS Healthcare Corporation
(Facsimile No. 615-846-3006).

                  4. The Subsidiary hereby waives acceptance by the
Administrative Agent and the Lenders of the guaranty by the Subsidiary under
Section 4 of the Credit Agreement upon the execution of this Agreement by the
Subsidiary.

                  5. This Agreement may be executed in two or more counterparts,
each of which shall constitute an original but all of which when taken together
shall constitute one contract.

                  6. This Agreement shall be governed by and construed and
interpreted in accordance with the laws of the State of New York.




                                       2
<PAGE>



                  IN WITNESS WHEREOF, the Subsidiary has caused this Joinder
Agreement to be duly executed by its authorized officers, and the Administrative
Agent, for the benefit of the Lenders, has caused the same to be accepted by its
authorized officer, as of the day and year first above written.



                                       IASIS FINANCE TEXAS HOLDINGS, LLC


                                       By:  /s/ Frank A. Coyle
                                           ----------------------------------
                                       Name: Frank A. Coyle
                                       Title: Secretary


                                       Acknowledged and accepted:

                                       BANK OF AMERICA, N.A.,
                                       as Administrative Agent


                                       By:    /s/ Kevin L. Ahart
                                             --------------------------------
                                       Name:  Kevin L. Ahart
                                             --------------------------------
                                       Title: Assistant Vice President
                                             --------------------------------




                                       3
<PAGE>



                                   SCHEDULE 1
               CHIEF EXECUTIVE OFFICE AND CHIEF PLACE OF BUSINESS

                          117 Seaboard Lane, Building E
                               Franklin, TN 37067


                                   SCHEDULE 2
                        TYPES AND LOCATIONS OF COLLATERAL

1.       Promissory Note in the principal amount of $7,837,327 issued by Odessa
         Regional Hospital, LP in favor of IASIS Finance Texas Holdings, LLC and
         related Allonge attached thereto;

2.       Promissory Note in the principal amount of $31,997,247 issued by Odessa
         Regional Hospital, LP in favor of IASIS Finance Texas Holdings, LLC and
         related Allonge attached thereto; and

3.       Promissory Note in the principal amount of $39,875,752 issued by
         Southwest General Hospital, LP in favor of IASIS Finance Texas
         Holdings, LLC and related Allonge attached thereto.


                                   SCHEDULE 3
                                   TRADENAMES

                        IASIS Finance Texas Holdings, LLC


                                   SCHEDULE 4
                             PATENTS AND TRADEMARKS

                                      None.


                                   SCHEDULE 5
                                SUBSIDIARY EQUITY

                                      None.






                                       4