<PAGE>


                                                                EXHIBIT 10.33.1



AMGEN            AMENDMENT #2 DATED FEBRUARY 10, 2003 TO AGREEMENT NO. 20010240
--------------------------------------------------------------------------------

This Amendment to Agreement No. 20010240 is being entered between Amgen USA
Inc., One Amgen Center Drive, Thousand Oaks, California 91320 ("Amgen") and
Renal Care Group, 2100 West End Avenue, Suite 800, Nashville, Tennessee 37203
including all affiliates that are listed on Appendix B (collectively, "RCG").

         WHEREAS, Amgen and RCG entered into Agreement No. 20010240 effective
         January 1, 2002: and

         WHEREAS, the parties now wish to amend the Agreement No. 20010240 to
         incorporate the terms and conditions for the purchase of Aranesp(R)
         (darbepoetin alfa) exclusively for the treatment of dialysiS patients,
         and to modify certain incentive option provisions.

         NOW, THEREFORE, in consideration of the premises and of the mutual
         covenants, representations and warranties set forth herein, the parties
         agree as follows:

SECTION 1. DEFINITIONS; REFERENCES. Unless otherwise specifically defined
     herein, each term used in this Amendment which is defined in the Agreement
     shall have the meaning assigned to such term in the Agreement. Except as
     amended and supplemented hereby, all of the terms of the Agreement are
     incorporated herein by reference, shall remain and continue in full force
     and effect, and are hereby ratified and confirmed in all respects.

SECTION 2. AMENDMENT TO SECTION 2, DIALYSIS CENTER AFFILIATES. Section 2 is
     hereby amended for the period April 1, 2003 through December 31, 2003, as
     follows:

2.   DIALYSIS CENTER AFFILIATES. Only those Affiliates approved by Amgen and
     referenced in Appendix B hereto will be eligible to participate under
     this Agreement. Modifications to the dialysis center Affiliates included in
     Appendix B may be made pursuant to the request of RCG's corporate
     headquarters and are subject to approval and acknowledgment by Amgen in
     writing. Notification of proposed changes to the list of Affiliates
     must be provided by RCG to Amgen in writing at least thirty (30) days
     before the effective date of the proposed change. Amgen reserves the
     right to accept, reject, or immediately terminate any Affiliates with
     regard to participation in this Agreement, if Amgen reasonably determines
     that such Affiliate is not properly classified as a freestanding dialysis
     center or * or if Amgen determines such Affiliate is a party to another *
     for EPOGEN(R) (Epoetin alfa)) or Aranesp(R) with Amgen.

SECTION 3. AMENDMENT TO SECTION 3, OWN USE. Section 3 is hereby amended for the
     period April 1, 2003 through December 31, 2003, as follows:

3.   OWN USE. RCG hereby certifies that EPOGEN(R) and Aranesp(R) (collectively,
     "Products") purchased hereunder shall be for RCG's "own use", for the
     exclusive treatment of dialysis patients.

SECTION 4. AMENDMENT TO SECTION 4, AUTHORIZED WHOLESALERS. Section 4 is hereby
     amended for the period April 1, 2003 through December 31, 2003, as follows:

4.   AUTHORIZED WHOLESALERS. Attached hereto as Appendix C is a complete list,
     as of the date of execution of this Amendment, of the wholesalers from
     which RCG intends to purchase Products. All of the wholesalers so
     designated by RCG are hereby approved by Amgen to participate in this
     program and are deemed "Authorized Wholesalers". Notification of proposed
     changes to the list of Authorized Wholesalers must be provided to Amgen
     in writing at least thirty (30) days before the effective date of the
     proposed change. Amgen reserves the right to accept, reject, or
     immediately terminate any wholesaler with regard to participation in
     this Agreement. In the event Amgen terminates any Authorized Wholesaler
     from which RCG is purchasing Products, Amgen will work with RCG to
     identify other possible Authorized Wholesalers from which RCG may
     purchase Products. In the event that RCG is unable to identify another
     Authorized Wholesaler from which RCG may purchase Products, and subject
     to receipt and approval of an *.


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

* Omitted information is the subject of a request for confidential treatment
  pursuant to Rule 24b-2 under the Securities Exchange Act of 1934 and has been
  filed separately with the Securities and Exchange Commission.


AGREEMENT NO. 20010240



<PAGE>


                 AMENDMENT #2 DATED FEBRUARY 10, 2003 TO AGREEMENT NO. 20010240
--------------------------------------------------------------------------------

     RCG agrees to require all Authorized Wholesalers to submit product sales
     information directly to Amgen and to a third-party sales reporting
     organization designated by Amgen.

SECTION 5. AMENDMENT TO SECTION 5, QUALIFIED PURCHASES. Section 5 is hereby
     amended for the period April 1, 2003 through December 31, 2003, as follows:

5.   QUALIFIED PURCHASES. Only Products purchased under this Agreement by RCG
     through *.

SECTION 6. AMENDMENT TO SECTION 6, COMMITMENT TO PURCHASE. Section 6 is hereby
     amended for the period April 1, 2003 through December 31, 2003, as follows:

6.   COMMITMENT TO PURCHASE. RCG agrees to purchase Products for all of its
     dialysis use requirements for recombinant human erythropoietin. RCG may
     purchase another brand of recombinant human erythropoietin for its dialysis
     use requirements only for the time, and only to the extent, that Amgen has
     notified RCG's corporate headquarters in writing that Amgen cannot supply
     Products within and for the time period reasonably required by RCG.

SECTION 7. AMENDMENT TO SECTION 10, DATA COLLECTION. Section 10 is hereby
     amended for the period April 1, 2003 through December 31, 2003, as follows:

10.  DATA COLLECTION. RCG agrees all data to be provided to Amgen pursuant to
     this Agreement shall be in a form that does not disclose the identity of
     any patient or any other patient-identifying information such as name,
     address, telephone number, birth date, all or part of a social security
     number, medical record number or prescription number. RCG and Amgen agree
     to use and accept only those patient identifiers compliant with the federal
     medical privacy standards codified under 45 C.F.R. parts 160 and 164
     pursuant to the Health Insurance Portability and Accountability Act
     ("HIPAA"). RCG acknowledges the data to be supplied to Amgen pursuant to
     this Agreement shall be used to support verification of the discounts and
     incentives referenced herein, as well as for Amgen-sponsored research
     concerning the role of EPOGEN(R) in improving treatment outcomes and
     quality of life of dialysis patients. RCG shall consistently use a unique
     alpha-numeric code (which shall not be the same as part or all of the
     patient's social security number) as a "case identifier" to track the care
     rendered to each individual patient over time, and such case identifier
     shall be included in the data provided to Amgen. The key or list matching
     patient identities to their unique case identifiers shall not be provided
     to Amgen personnel. In furtherance of Amgen research, RCG may agree from
     time to time to use its key to update the patient care data by linking it
     with information concerning health outcomes, quality of life, and other
     pertinent data that may become available to Amgen from other sources. Any
     such linking of data sources shall not provide the identity of any patient
     to Amgen. Amgen agrees it will maintain data supplied under this Agreement
     in confidence and it will not use such data to identify or contact any
     patient. No reports by Amgen concerning analyses of the data or the results
     of such research shall disclose the identity of any patient.

SECTION 8. AMENDMENT TO SECTION 15, COMPLIANCE WITH HEALTH CARE PRICING AND
     PATIENT PRIVACY LEGISLATION AND STATUTES. Section 15 is hereby amended and
     restated for the period April 1, 2003 through December 31, 2003, as
     follows:

15.  COMPLIANCE WITH HEALTH CARE PRICING AND PATIENT PRIVACY LEGISLATION AND
     STATUTES; DATA USE AGREEMENT.

     (a) Notwithstanding anything contained herein to the contrary, at any time
         following the enactment of any federal, state, or local law or
         regulation that in any manner reforms, modifies, alters, restricts, or
         otherwise affects the pricing of or


                                      -2-

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

*  Omitted information is the subject of a request for confidential treatment
   pursuant to Rule 24b-2 under the Securities Exchange Act of 1934 and has been
   filed separately with the Securities and Exchange Commission.

AGREEMENT NO. 20010240
<PAGE>


                 AMENDMENT #2 DATED FEBRUARY 10, 2003 TO AGREEMENT NO. 20010240
--------------------------------------------------------------------------------

     reimbursement available for Products, including but not limited to a
     reimbursement or use decision by Centers for Medicare and Medicaid Services
     ("CMS"), Amgen may, in its sole discretion, exclude any Affiliates from
     participating in this Agreement upon thirty (30) days notice, unless such
     Affiliates certifies in writing that they are, or will be, exempt from the
     provisions thereunder. Additionally, to assure compliance with any existing
     federal, state or local statute, regulation or ordinance, Amgen reserves
     the right, in its sole discretion, to exclude any Affiliates from the
     pricing and discount provisions of this Agreement and/or to reasonably
     modify any pricing or discount terms contained herein. In the event there
     is a future change in Medicare. Medicaid, or other federal or state
     statute(s) or regulation(s) or in the interpretation thereof, which renders
     any of the material terms of this Agreement unlawful or unenforceable this
     Agreement shall continue only if amended by the parties as a result of good
     faith negotiations as necessary to bring the Agreement into compliance with
     such statute or regulation.

     (b) Notwithstanding anything contained herein to the contrary, at any time
     following the enactment of any federal, state, or local law or regulation
     relating to patient privacy of medical records that in any manner reforms,
     modifies, alters, restricts, or otherwise affects any of the data received
     or to be received in connection with any of the incentives contemplated
     under this Agreement, either party may, in its discretion, upon thirty (30)
     days' notice, seek to modify this Agreement with respect to the affected
     incentive. RCG and Amgen shall meet and in good faith seek to mutually
     agree to modify this Agreement to accommodate any such change in law or
     regulation, with the intent to, if possible, retain the essential *
     structure of the affected incentive. If the parties, after reasonable time,
     are unable to agree upon a modification, Amgen shall be entitled to
     terminate the affected incentive upon thirty (30) days' notice or upon such
     date that the law or regulation requires, whichever is earlier.

     (c) Notwithstanding anything contained herein to the contrary, this
     Agreement is effective only as of the date the parties hereto execute a
     mutually agreeable Data Use Agreement pursuant to which RCG may disclose a
     Limited Data Set of patient information to Amgen (as specified in the Data
     Use Agreement and which shall include, at a minimum, the data fields to be
     received by Amgen in connection with this Agreement) for purposes of
     Amgen's * and * analyses and RCG's Health Care Operations. Unless otherwise
     specifically defined in this Agreement, each capitalized term used in this
     Section 15(c) shall have the meaning assigned to such term by HIPAA. If RCG
     terminates the Data Use Agreement for any reason, Amgen shall be entitled
     to terminate this Agreement immediately.

SECTION 9. AMENDMENT TO APPENDIX A. DISCOUNT PRICING, SCHEDULE, AND TERMS.
     Appendix A is hereby amended for the period April 1, 2003 through December
     31, 2003, as follows:

1.   PRICING - ARANESP(R). During the *, RCG may purchase Aranesp(R) through *
     at a *. Amgen reserves the right to change the * at any time. Resulting
     prices do not include *.  *.

2.   PRICING - EPOGEN(R). During the *, RCG may purchase EPOGEN(R) through * at
     an *, which shall be equal * IN effect on *. Amgen reserves the right to
     change the * at any time, which change shall * RCG during the Term of this
     Agreement. Resulting prices do not include *. All discounts earned in
     arrears during the * shall be calculated based *.

3.   BASE SALES; SALES GROWTH CALCULATION. For purposes of * from *, Amgen will
     * for the * by all Affiliates listed on Appendix B on the effective date of
     this Amendment and, as provided for in this Section 2, all new approved
     Affiliates. For new approved Affiliates added through acquisition, * by
     such new approved Affiliates shall only be * if RCG provides adequate data
     to Amgen's reasonable satisfaction concerning such new approved Affiliates'
     *. *.

4.   *. RCG may qualify for * provided it meets the * defined below and the
     criteria described below in this section. * is designed to improve patient
     outcomes by encouraging * which recommends *.*


                                      -3-

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

*  Omitted information is the subject of a request for confidential treatment
   pursuant to Rule 24b-2 under the Securities Exchange Act of 1934 and has been
   filed separately with the Securities and Exchange Commission.


AGREEMENT NO. 20010240
<PAGE>

                 AMENDMENT #2 DATED FEBRUARY 10, 2003 TO AGREEMENT NO. 20010240
--------------------------------------------------------------------------------

     A. REQUIREMENTS: In order to qualify for *, RCG's aggregate * of EPOGEN(R)
     during * and aggregate * of EPOGEN(R) and Aranesp(R) during * by all
     Affiliates as listed on Appendix B on the effective date of this Amendment
     must *, of the

     aggregate * of EPOGEN(R) by those same Affiliates *. In addition, no more
     than * may have * during each * oF the Term. If either of these criteria is
     not met during any given * of the Term, RCG will not qualify for the *
     during that *. Failure of RCG to qualify for the * during a particular *.
     If at the end of * the * has been met, then Amgen * for * and appropriately
     * for those relevant * during * in which a * was not *. However, if at the
     end of * the * has not been met, * for *. * will be made by Amgen or RCG,
     as the case may be, within * after the end of *, *. In order to participate
     *, RCG and Affiliates must provide the following information for each
     dialysis patient to Amgen or to a data collection vendor specified by Amgen
     *, and * after the *:

          i)  all * for each dialysis patient, the date of each test, and a
              consistent, unique, alphanumeric identifier (sufficient
              consistently to track an individual patient without in any way
              violating the de-identification provisions of HIPAA at 45 CFR
              164.514), along with the name, address and phone number of the
              particular Affiliate at which each patient received treatment
              (collectively the "Data"). To the extent permitted by applicable
              law, Amgen may utilize the Data for any purpose, and reserves the
              right to audit all Data. Under no circumstances should the Data
              include any patient identifiable information including, without
              limitation, name, all or part of social security number, address
              medical record number, or prescription number. The identity of the
              account submitting the Data and any association with the Data will
              remain confidential. The * must be derived from * taken
              immediately before dialysis treatment using any * testing method
              (*), must be reported *, and must be submitted directly from the
              clinical laboratory in a format reasonably acceptable to Amgen.
              Handwritten reports are not acceptable; only electronic submission
              of the Data will be accepted, and

         ii)  upon execution of this Amendment, RCG shall simultaneously provide
              to Amgen an executed "Certification Letter", a copy of which is
              attached hereto as Exhibit #1. Amgen hereby acknowledges that it
              has received such required Certification Letter, in a form and
              substance satisfactory to Amgen. Delivery of such Certification
              Letter shall serve to qualify RCG's participation in the *
              throughout the * of this Agreement for the limited purpose of
              certification of the accuracy of the data submitted to Amgen
              hereunder.

B. CALCULATION: Assuming RCG has fulfilled all requirements as described in
   Section 4(a) above, RCG's * will be calculated as follows:

The * for each dialysis patient will be based upon the average of all * gathered
for each patient during * of *. The * of all dialysis patients with *, will be
determined by dividing the total number of dialysis patients with *. * will be
calculated based on RCG's overall performance in accordance with Amgen's
discount calculation policies.

C. PAYMENT: * will be calculated on a * and paid to RCG's corporate
headquarters, except as otherwise provided hereunder. Payment is contingent upon
receipt by Amgen of the "Certification Letter" and *. If Data is received more
than * after *, the total * of EPOGEN(R) and Aranesp(R) attributable to RCG
during * for that *. Notwithstanding the foregoing, if Amgen receives all
required Data from * of all Affiliates within the time frame referenced above
for *, the total * of EPOGEN(R) and Aranesp(R) attributable to RCG during *,
will be included in THE calculation of * for that *. However, if Amgen
determines that any Affiliate is consistently not submitting the required Data,
Amgen reserves the right in its sole discretion to exclude such Affiliate's * of
EPOGEN(R) anD Aranesp(R) from the calculation * for any *. * payments will be
based upon the Data received from the *, and wilL equal a percentage of RCG's
total * of EPOGEN(R) and Aranesp(R) during that * (exclusive of any * of
EPOGEN(R) AND Aranesp(R) made by RCG or any Affiliate not meeting the Data
submission requirements described above) as governeD by * schedule listed below.
Notwithstanding the foregoing, payment for any period during the * that is not
equivalent to a * will be based *. If the EPOGEN(R) or Aranesp(R) * or the *,
then Amgen and RCG agree *. * above.



                                      -4-
----------------------
*  Omitted information is the subject of a request for confidential treatment
   pursuant to Rule 24b-2 under the Securities Exchange Act of 1934 and has been
   filed separately with the Securities and Exchange Commission.

AGREEMENT NO. 20010240
<PAGE>

                 AMENDMENT #2 DATED FEBRUARY 10, 2003 TO AGREEMENT NO. 20010240
--------------------------------------------------------------------------------


                                   * SCHEDULE
                                        *



PLEASE DIRECT YOUR ATTENTION TO THE EPOGEN(R) PACKAGE INSERT

                           *




     D. VESTING:  RCG's * will vest at the *.

     E. * SUBMISSION: To participate in the *, RCG must * submit *, rather than
     *. Such * must be submitted for all dialysis patients at each Affiliate
     along with all other information described in Section 4(a) above. Amgen no
     longer accepts *.

5.   *. RCG shall be eligible to receive * if certain data  elements are
     transmitted to Amgen *. The * will be calculated as a percentage of the
     * of EPOGEN(R)attributable to RCG during *. In order to qualify for the
     *, the following * must be submitted to Amgen by all Affiliates pursuant to
     Section 15(c) *. The * must be submitted, on a *, and *. If the * are
     received * within a given *, the total * of EPOGEN(R) attributable to
     RCG * from the calculation of the * for that *. Notwithstanding the
     foregoing, if Amgen receives all required * within the time frame
     referenced above for any *, the total * of EPOGEN(R)attributable to RCG
     during such *, will be * of the * for that *. However, if Amgen determines
     that any Affiliate is consistently *, Amgen and RCG will work *. Amgen
     reserves the right, in its sole discretion, to exclude any such
     non-reporting Affiliate's * of EPOGEN(R) from the calculation of the *
     for any relevant *. The * will vest on the last day of the corresponding *,
     and will be paid * thereafter.

6.   *.  RCG may qualify for the * as described below.

     A. CALCULATION: RCG's * will be calculated in accordance with the following
     formula.

                                        *



                                      -5-


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

*  Omitted information is the subject of a request for confidential treatment
   pursuant to Rule 24b-2 under the Securities Exchange Act of 1934 and has been
   filed separately with the Securities and Exchange Commission.

AGREEMENT NO. 20010240

<PAGE>





                 AMENDMENT #2 DATED FEBRUARY 10, 2003 TO AGREEMENT NO. 20010240
--------------------------------------------------------------------------------


     B. VESTING: RCG's * will vest *.  * and the * amount earned.

7.   *


Please retain one fully executed original for your records and return the other
fully executed original to Amgen.

     THE PARTIES EXECUTED THIS AMENDMENT AS OF THE DATES SET FORTH BELOW.

     AMGEN USA INC.                          RENAL CARE GROUP, INC.

     Signature:                              Signature:
                  -----------------------                -----------------------

     Print Name:                             Print Name:
                  -----------------------                -----------------------

     Print Title:                            Print Title:
                  -----------------------                -----------------------

     Date:                                   Date:
                  -----------------------                -----------------------



                                      -6-

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

*  Omitted information is the subject of a request for confidential treatment
   pursuant to Rule 24b-2 under the Securities Exchange Act of 1934 and has been
   filed separately with the Securities and Exchange Commission.

AGREEMENT NO. 20010240


<PAGE>



                 AMENDMENT #2 DATED FEBRUARY 10, 2003 TO AGREEMENT NO. 20010240
--------------------------------------------------------------------------------


                       APPENDIX B: LIST OF RCG AFFILIATES

                                 To be Attached

TO ENSURE YOU RECEIVE THE APPROPRIATE DISCOUNT, IT IS IMPORTANT THAT WE HAVE
YOUR CURRENT LIST OF AUTHORIZED WHOLESALERS. THE FOLLOWING LIST REPRESENTS THE
WHOLESALERS AMGEN CURRENTLY HAS ASSOCIATED WITH YOUR CONTRACT.. PLEASE UPDATE
THE LIST BY ADDING OR DELETING WHOLESALERS AS NECESSARY.

Metro Medical Supply Inc.
3332 Powell Avenue
Nashville, TN 37204





                                      -7-
AGREEMENT NO. 20010240

<PAGE>



                                                                      Exhibit #1


                           Sample Certification Letter

, 2003

Renal Care Group, Inc.
2525 West End Avenue, Suite 600
Nashville, TN 37203

RE: Amendment #2 to Agreement No. 20010240

Dear                       :
     ----------------------

Thank you for your participation in *. In order for us to enroll you, we require
that a duly authorized representative of your organization sign the
certification below.

Upon receipt of this executed document, we will calculate the value of your *.
If we do not receive the executed certification, we cannot provide you with this
*.

If you have any questions regarding this letter please contact me at *. Thank
you for your assistance in returning this certification.

Sincerely,


*
*

CERTIFICATION:

On behalf of Renal Care Group, Inc., and all eligible Affiliates participating
in * under Agreement No. 20010240, the undersigned hereby certifies that the *
required to be submitted (herein referred to as "*"), for each eligible
Affiliate during the term of this Agreement includes the required * from all
dialysis patients from each such Affiliate, *. The party executing this document
also represents and warrants that it (i) has no reason to believe that the
submitted * is incorrect, and (ii) is authorized to make this certification on
behalf of all eligible Affiliates submitting *.

FSDC LEGAL NAME

Signature:
             ------------------------------

Print Name:
             ------------------------------

Print Title:
             ------------------------------

Date:
             ------------------------------



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

*  Omitted information is the subject of a request for confidential treatment
   pursuant to Rule 24b-2 under the Securities Exchange Act of 1934 and has been
   filed separately with the Securities and Exchange Commission.

AGREEMENT NO. 20010240