<PAGE>
                                                                   EXHIBIT 10.36

                                                                  EXECUTION COPY






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                         PACIFICARE HEALTH SYSTEMS INC.

                        ---------------------------------



                                 AMENDMENT NO. 2

                                   dated as of

                                December 17, 2003

                                       to

                                CREDIT AGREEMENT

                                   dated as of

                                  June 3, 2003

                        ---------------------------------


                              JPMORGAN CHASE BANK,
                             as Administrative Agent

                        ---------------------------------



                           J.P. MORGAN SECURITIES INC.
                                       and
                      MORGAN STANLEY SENIOR FUNDING, INC.,
          as Joint Advisors, Joint Lead Arrangers and Joint Bookrunners


================================================================================



<PAGE>

                                 AMENDMENT NO. 2

         AMENDMENT NO. 2 dated as of December 17, 2003 to the Credit Agreement
referred to below, between: PACIFICARE HEALTH SYSTEMS INC. (the "Borrower"); the
Subsidiary Guarantors party to the Credit Agreement; and JPMORGAN CHASE BANK, as
Administrative Agent thereunder.

         The Borrower, the Subsidiary Guarantors, the Lenders, the
Administrative Agent and the Collateral Agent are parties to a Credit Agreement
dated as of June 3, 2003 (as amended and in effect from time to time, the
"Credit Agreement"), providing, subject to the terms and conditions thereof, for
extensions of credit to be made by the Lenders to the Borrower.

         The Borrower has requested certain amendments to the Credit Agreement
and, accordingly, the parties hereto hereby agree as follows:

         Section 1. Definitions. Except as otherwise defined in this Amendment
No. 2, terms defined in the Credit Agreement are used herein as defined therein.

         Section 2. Amendments. Subject to the satisfaction of the conditions
precedent specified in Section 4 hereof, but effective as of the date hereof,
the Credit Agreement shall be amended as follows:

         2.01. General References. References in the Credit Agreement (including
references to the Credit Agreement as amended hereby) to "this Agreement" (and
indirect references such as "hereunder", "hereby", "herein" and "hereof") shall
be deemed to be references to the Credit Agreement as amended hereby.

         2.02. Definitions. Section 1.01 of the Credit Agreement is amended by
adding the following new defined term in its appropriate alphabetical location:

         "Applicable Term Loan Margin" means for any day, with respect to any
     ABR Loan or Eurodollar Loan, the applicable rate per annum set forth below
     under the caption "ABR Spread" or "Eurodollar Spread", respectively, based
     upon the Ratings applicable on such date to the Loans (each a "Rating"):

<TABLE>
<CAPTION>

                                      Ratings                       ABR                    Eurodollar
                                   (S&P/Moody's)                   Spread                    Spread
                                  ---------------                 --------                 -----------

<S>                         <C>                                 <C>                      <C>
          Category 1        > or = BB+ and > or = Ba2               1.25%                    2.25%


                                BB and > or = Ba2

          Category 2                                                1.50%                    2.50%
                               > or = BB and Ba3

                                 Other than in
          Category 3             Category 1 or 2                    1.75%                    2.75%

</TABLE>


                                 Amendment No. 2

<PAGE>

                                     - 2 -

         For purposes of the foregoing, (a) if one of S&P and Moody's shall not
     have in effect a Rating (other than by reason of the circumstances referred
     to in the last sentence of this definition), such rating agency shall be
     deemed to have a Rating equal to the level of the Rating of the other
     rating agency; (b) if neither S&P nor Moody's shall have in effect a Rating
     (other than by reason of the circumstances referred to in the last sentence
     of this definition), then each such rating agency shall be deemed to have
     established a Rating in Category 3; and (c) if the Ratings established or
     deemed to have been established by S&P and Moody's shall be changed (other
     than as a result of a change in the rating system of S&P or Moody's), such
     change shall be effective as of the date on which it is first announced by
     the applicable rating agency. Each change in the Applicable Term Loan
     Margin shall apply during the period commencing on the effective date of
     such change and ending on the date immediately preceding the effective date
     of the next such change; provided that no reduction in the Applicable Term
     Loan Margin shall be effective for so long as an Event of Default shall
     have occurred and be continuing. If the rating system of S&P or Moody's
     shall change, or if either such rating agency shall cease to be in the
     business of rating secured bank loans, the Borrower and the Lenders shall
     negotiate in good faith to amend this definition to reflect such changed
     rating system or the unavailability of ratings from such rating agency and,
     pending the effectiveness of any such amendment, the Applicable Term Loan
     Margin shall be determined by reference to the rating most recently in
     effect prior to such change or cessation.

         The Applicable Term Loan Margin in effect on effective date of
     Amendment No. 2 hereto dated as of December 17, 2003 shall be (i) in the
     case of Term Loans constituting an ABR Borrowing shall be 1.75% per annum
     and (ii) in the case of Term Loans constituting a Eurodollar Borrowing
     shall be 2.75% per annum.

         2.03. Interest on ABR Term Loans. Section 2.11(a)(ii) shall be amended
to read in its entirety as follows:

         "(ii) the Alternate Base Rate plus the Applicable Term Loan Margin (in
     the case of Term Loans constituting an ABR Borrowing)."

         2.04. Interest on Eurodollar Term Loans. Section 2.11(b)(ii) shall be
amended to read in its entirety as follows:

         "(ii) the Adjusted LIBO Rate for the Interest Period for such Borrowing
     plus the Applicable Term Loan Margin (in the case of Term Loans
     constituting a Eurodollar Borrowing)."

         Section 3. Representations and Warranties. The Borrower represents and
warrants to the Lenders as of the date hereof that (a) the representations and
warranties of the Borrower set forth in the Credit Agreement are true and
correct, and of each Obligor in each of the other Loan Documents to which it is
a party are true and correct in all material respects, in each case on and as of
the date hereof with the same force and effect as if made on and as of the date
hereof (or, if any such representation and warranty is expressly stated to have
been made as





                                 Amendment No. 2

<PAGE>

                                      - 3 -

of a specific date, as of such specific date) and as if each reference herein to
"this Agreement" (or words of similar import) or in such other Loan Documents to
"the Credit Agreement" (or words of similar import) included reference to this
Amendment No. 2 and (b) no Default has occurred and is continuing.

         Section 4. Conditions Precedent. The amendments to the Credit Agreement
set forth in Section 2 shall become effective as of the date hereof upon receipt
by the Administrative Agent of one or more counterparts of this Amendment No. 2
executed by each Obligor and the Administrative Agent (with the written consent
of each of the Term Loan Lenders and the Required Lenders provided in the form
of the Lender Consent attached hereto as Exhibit A).

         Section 5. Confirmation of Guarantees and Security Interests. The
Obligors hereby confirms and ratifies all of its respective obligations under
the Loan Documents to which it is a party (including, in the case of each
Subsidiary Guarantor, its respective obligations as a guarantor under Article
III of the Credit Agreement (as amended hereby)) and the Liens granted by it
under the respective Loan Documents (as amended hereby) and hereby represent,
warrant and confirm that all references in such Loan Documents to the Credit
Agreement (or words of similar import) fully and effectively mean the Credit
Agreement as amended hereby without impairing any such obligations or Liens in
any respect.

         Section 6. Miscellaneous. Except as herein provided, the Credit
Agreement shall remain unchanged and in full force and effect. This Amendment
No. 2 may be executed in any number of counterparts, all of which taken together
shall constitute one and the same amendatory instrument and any of the parties
hereto may execute this Amendment No. 2 by signing any such counterpart. This
Amendment No. 2 shall be governed by, and construed in accordance with, the law
of the State of New York.




                                 Amendment No. 2
<PAGE>


                                     - 4 -

         IN WITNESS WHEREOF, the parties hereto have caused this Amendment No. 2
to be duly executed and delivered as of the day and year first above written.



                                    BORROWER

                                    PACIFICARE HEALTH SYSTEMS, INC.



                                    By
                                      ------------------------------------------
                                      Name:
                                      Title:



                                 Amendment No. 2

<PAGE>

                                      -5-


                                    SUBSIDIARY GUARANTORS

                                    PACIFICARE HEALTH PLAN
                                    ADMINISTRATORS, INC.



                                    By
                                      ------------------------------------------
                                      Name:
                                      Title:



                                    PACIFICARE eHOLDINGS, INC.



                                    By
                                      ------------------------------------------
                                      Name:
                                      Title:



                                    SENIORCO, INC.



                                    By
                                      ------------------------------------------
                                      Name:
                                      Title:



                                    RxSOLUTIONS, INC.



                                    By
                                      ------------------------------------------
                                      Name:
                                      Title:


                                 Amendment No. 2

<PAGE>
                                      -6-


                                    PACIFICARE BEHAVIORAL HEALTH, INC.



                                    By
                                      ------------------------------------------
                                      Name:
                                      Title:



                                    SECUREHORIZONS USA, INC.



                                    By
                                      ------------------------------------------
                                      Name:
                                      Title:



                                    PACIFICARE OF ARIZONA, INC.



                                    By
                                      ------------------------------------------
                                      Name:
                                      Title:



                                    PACIFICARE OF OKLAHOMA, INC.



                                    By
                                      ------------------------------------------
                                      Name:
                                      Title:



                                 Amendment No. 2

<PAGE>

                                     - 7 -

                                    ADMINISTRATIVE AGENT

                                    JPMORGAN CHASE BANK,
                                      as Administrative Agent



                                    By
                                      ------------------------------------------
                                      Name:
                                      Title:



<PAGE>

                                                                       EXHIBIT A

                                 LENDER CONSENT

                  Reference is made to the Credit Agreement dated as of June 3,
2003 (as amended and in effect from time to time, the "Credit Agreement")
between Pacificare Health Systems Inc., the Subsidiary Guarantors party to the
Credit Agreement, the Lenders party to the Credit Agreement, JPMorgan Chase
Bank, as Administrative Agent thereunder and JPMorgan Chase Bank, as Collateral
Agent thereunder. Capitalized terms used and not otherwise defined herein are
deemed to have the respective meanings assigned to such terms in the Credit
Agreement.

                  The undersigned Lender party to the Credit Agreement hereby
(i) consents to Amendment No. 2 to the Credit Agreement, dated as of December
17, 2003, substantially in the form to which the form of this Lender Consent is
attached ("Amendment No. 2") and (ii) authorizes and directs the Administrative
Agent to execute and deliver Amendment No. 2 on behalf of such Lender.





Full Name of Lender:
                    ---------------------------------------


By:
    ---------------------------------------
    Name:
    Title:

Date:  December 17, 2003




                                 Amendment No. 2