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                                                                    EXHIBIT 4.06

                             SUPPLEMENTAL INDENTURE

         This Supplemental Indenture (this "SUPPLEMENTAL INDENTURE") dated as of
September 15, 2003, by and between PacifiCare Health Systems, Inc., a Delaware
corporation (the "COMPANY"); PacifiCare Health Plan Administrators, Inc., an
Indiana corporation, PacifiCare eHoldings, Inc., a California corporation,
RxConnect, Inc., a California corporation and SeniorCo, Inc., a Delaware
corporation (collectively, the "INITIAL SUBSIDIARY GUARANTORS"); Rx Solutions,
Inc., a California corporation, PacifiCare Behavioral Health, Inc., a Delaware
corporation and Secure Horizons USA, Inc., a California corporation
(collectively, the "PHPA SUBSIDIARY GUARANTORS"); and U.S. Bank National
Association, a national banking association, as successor to State Street Bank
and Trust Company of California, N.A., as trustee under the Indenture referred
to below (the "TRUSTEE"). Capitalized terms used but not defined herein shall
have the meanings given to them in the Indenture referred to below.

                                    RECITALS

         WHEREAS, the Company and the Initial Subsidiary Guarantors heretofore
executed and delivered to the Trustee an Indenture (the "INDENTURE") dated as of
May 21, 2002 providing for the issuance of an aggregate principal amount of
$500,000,000 of 10 3/4% Senior Notes due 2009 (the "NOTES");

         WHEREAS, Section 4.07 of the Indenture provides that, immediately upon
the prepayment, redemption, purchase, defeasance or other satisfaction in full
of the 7% Senior Notes due 2003 (the "7% SENIOR NOTES DUE 2003") issued by FHP
International Corporation (subsequently renamed PacifiCare Health Plan
Administrators, Inc. [FHP INTERNATIONAL WAS ACTUALLY MERGED INTO PHPA;
THEREFORE, WE PROBABLY SHOULD SAY THIS DIFFERENTLY, I.E., NOW KNOWN AS PHPA BY
VIRTUE OF THE MERGER OF THESE ENTITIES]) pursuant to the terms of that certain
indenture dated as of September 22, 1993 between FHP International Corporation
and The Chase Manhattan Bank, N.A. [WE MAY WANT TO REFER TO THE SUPPLEMENTAL
INDENTURE DATED 1996-1997 BY WHICH OLD PHS BECAME THE OBLIGOR UNDER THE FHP
NOTES SINCE THE OLD PHS ENTITY LATER MERGED INTO PHPA MAKING PHPA THE OBLIGOR],
the Company will cause each PHPA Subsidiary Guarantor to fully and
unconditionally Guarantee, jointly and severally, on an unsecured unsubordinated
basis the payment of principal, premium, if any, and interest on the Notes by
the execution and delivery of a supplemental indenture to the Indenture;

         WHEREAS, the 7% Senior Notes due 2003 matured on September 15, 2003 and
have been defeased in full;

         WHEREAS, pursuant to Section 9.01 of the Indenture, the Trustee, the
Company and the Subsidiary Guarantors [SECTION 9.01 REFERS TO "SUBSIDIARY
GUARANTORS" WHICH INCLUDES THE INITIAL SUBSIDIARY GUARANTORS, THE PHPA
GUARANTORS AND ANY OTHER RESTRICTED SUBSIDIARY THAT LATER PROVIDES A NOTE
GUARANTEE OF THE COMPANY'S OBLIGATIONS] are authorized, without notice to or the
consent of any Holder, to execute and deliver this Supplemental Indenture to
cause the PHPA Subsidiary Guarantors to Guarantee the Notes to comply with
Section 4.07 of the Indenture; and

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         WHEREAS, the Company, the Trustee, the Initial Subsidiary Guarantors
and the PHPA Subsidiary Guarantors desire to enter into this Supplemental
Indenture to provide for such Note Guarantees as contemplated by Section 4.07 of
the Indenture.

                                   AGREEMENT

         NOW, THEREFORE, in consideration of the foregoing and for other good
and valuable consideration, the receipt of which is hereby acknowledged, the
Company, the Initial Subsidiary Guarantors, the PHPA Subsidiary Guarantors and
the Trustee mutually covenant and agree as follows:

         1. CREATION OF NOTE GUARANTEE. Each PHPA Subsidiary Guarantor hereby
agrees, jointly and severally with all other Subsidiary Guarantors, to Guarantee
the Notes and the performance of the Company's obligations under the Notes and
the Indenture in accordance with the terms and provisions of Article Ten of the
Indenture. Each PHPA Subsidiary Guarantor shall be bound by, and entitled to the
benefits of, all other applicable terms and provisions of the Indenture as a
Subsidiary Guarantor, including the provisions relating to the release of the
Note Guarantees in certain circumstances.

         2. RATIFICATION OF INDENTURE; SUPPLEMENTAL INDENTURE PART OF INDENTURE.
Except as expressly amended hereby, the Indenture is in all respects ratified
and confirmed and all the terms, conditions and provisions thereof shall remain
in full force and effect. This Supplemental Indenture shall form a part of the
Indenture for all purposes, and every holder of the Notes heretofore or
hereafter authenticated and delivered shall be bound hereby.

         3. GOVERNING LAW. THIS SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY THE
LAWS OF THE STATE OF NEW YORK.

         4. TRUSTEE MAKES NO REPRESENTATION. The Trustee makes no representation
as to the validity or adequacy of this Supplemental Indenture.

         5. COUNTERPARTS. The parties may sign any number of copies of this
Supplemental Indenture. Each signed copy shall be an original, but all of them
together represent the same agreement.

         6. EFFECT OF HEADINGS. The Section headings herein are for convenience
only and shall not effect the construction thereof.


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         IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed as of the date first written above.


                                            PACIFICARE HEALTH SYSTEMS, INC.


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


                                            PACIFICARE HEALTH PLAN
                                            ADMINISTRATORS,  INC.

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

                                            PACIFICARE EHOLDINGS, INC.

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

                                            RXCONNECT, INC.

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

                                            SENIORCO, INC.

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

                                            RX SOLUTIONS, INC.

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

                                            PACIFICARE BEHAVIORAL HEALTH, INC.

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


                                            SECUREHORIZONS USA, INC.

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



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                                            U.S. BANK NATIONAL ASSOCIATION


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