<PAGE>
                                                                EXHIBIT 10.19.3

AMGEN                           AMENDMENT NO. 1 RENAL CARE GROUP, INC. AGREEMENT
NO. 200308361
--------------------------------------------------------------------------------

The undersigned hereby agree to amend Agreement No. 200308361 (the "Agreement")
between Amgen USA Inc., located at One Amgen Center Drive, Thousand Oaks,
California 91320 ("Amgen") and Renal Care Group, Inc., located at 2525 West End
Avenue, Suite 600, Nashville, Tennessee 37203 ("RCG") including any prior
amendments thereto, as stated below.

WHEREAS, Amgen and RCG entered into Agreement No. 200308361 effective January 1,
2004;

WHEREAS, the Agreement sets forth the terms and conditions for the purchase of
EPOGEN(R) (Epoetin alfa) and Aranesp(R) (darbepoetin alfa) (collectively,
"Products") by RCG, exclusively for the treatment of dialysis patients; and

WHEREAS, the parties wish to amend this Agreement to modify the term of the
Agreement, offer a Commitment Incentive for the period Amended Date through
December 31, 2004, modify rebate programs for the period January 1, 2005 through
December 31, 2005, and offer new rebates for the period January 1, 2005 through
December 31, 2005.

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. AMENDMENT AND RESTATEMENT OF THE GENERAL TERMS AND CONDITIONS - THE
GENERAL TERMS AND CONDITIONS OF THE AGREEMENT SHALL BE AMENDED AND RESTATED IN
THEIR ENTIRETY EFFECTIVE AS FOLLOWS ON DECEMBER 1, 2004 PROVIDED RCG EXECUTES
THIS AMENDED AGREEMENT ON OR BEFORE DECEMBER 1, 2004 ("AMENDED DATE"). IF RCG
EXECUTES THIS AMENDED AGREEMENT AFTER DECEMBER 1, 2004, THE AMENDED DATE SHALL
BE THE DATE ON WHICH THE PARTY LAST TO EXECUTE THIS AMENDED AGREEMENT HAS
EXECUTED THIS AMENDED AGREEMENT.

1.       TERM OF AGREEMENT. The "Term" of this Agreement shall be defined as
         January 1, 2004 ("Commencement Date") through December 31, 2005
         ("Termination Date").

2.       RCG AFFILIATES. RCG must provide Amgen with a complete list of its
         dialysis center affiliates ("Affiliates") on the date this Agreement is
         executed by RCG. Only those Affiliates approved by Amgen and referenced
         in Appendix B hereto will be eligible to participate under this
         Agreement. Modifications to the 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 home dialysis support facility or if Amgen determines such
         Affiliate is a party to another purchase agreement for EPOGEN(R) or
         Aranesp(R) with Amgen.

3.       AFFILIATE ACQUISITIONS. Should RCG acquire additional Affiliates during
         the Term, and such acquisitions result in an aggregate incremental
         increase in total prior year base sales by more than * Million Dollars
         ($*), then Amgen and RCG agree to meet and in good faith review the
         Agreement in light of the evolving business conditions. For purposes of
         this section, base sales will be derived using the rolling twelve (12)
         month period immediately



----------
* 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.


<PAGE>

                             AMENDMENT NO. 1 AGREEMENT NO. 200308361 (CONTINUED)
--------------------------------------------------------------------------------

         preceding the Affiliate acquisition that causes RCG to meet the *
         Million Dollars ($*) limitation, and using the * in effect at *.

4.       OWN USE. RCG hereby certifies that Products purchased hereunder shall
         be for RCG's "own use", for the exclusive treatment of dialysis
         patients.

5.       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 pursuant to this Agreement.
         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 *. 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.

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

7.       COMMITMENT TO PURCHASE. RCG agrees to exclusively purchase Products for
         all of its dialysis use requirements for erythropoietic stimulating
         protein. RCG may purchase another brand of erythropoietic stimulating
         protein 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 or for use by any Affiliate that has
         been rejected or excluded by Amgen from participating in this Agreement
         pursuant to any provision of this Agreement.

8.       CONFIDENTIALITY. Both Amgen and RCG agree that this Agreement
         represents and contains confidential information which shall not be
         disclosed to any third party, or otherwise made public, without prior
         written authorization of the other party, except where such disclosure
         is contemplated hereunder or required by law, and then only upon prior
         written notification to the other party.

9.       DISCOUNTS. RCG may qualify for discounts and incentives in accordance
         with the schedules and terms set forth in Appendix A. Discounts in
         arrears will be paid in the form of a check payable to RCG's corporate
         headquarters. Discounts in arrears will be calculated in accordance
         with Amgen's discount calculation policies based on * using the
         prevailing * in effect as of the date of purchase as the calculation
         price, except as otherwise provided hereunder. Upon vesting of all
         earned discounts, Amgen will use its best efforts to make such
         discounts available no later than * after receipt by Amgen of complete
         and machine readable data, in a form acceptable to Amgen, detailing all
         * during the applicable period. Discount amounts, as calculated by
         Amgen, must equal or exceed $* for the applicable period to qualify.
         Subject to Section 12, in the event that Amgen is notified in writing
         that RCG and/or any Affiliates are acquired by another entity or a
         change of control otherwise occurs with respect to RCG or an Affiliate,
         any discounts which may have been earned hereunder shall be paid in the
         form of a check payable to RCG's or the Affiliate's corporate
         headquarters subject to the conditions described herein. If any
         Affiliates are added to or deleted from this Agreement during any of
         the periods used for comparison, for any of the discounts paid in
         arrears contained herein, Amgen reserves the right in its sole and



----------
* 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.


                                      -2-
<PAGE>
                             AMENDMENT NO. 1 AGREEMENT NO. 200308361 (CONTINUED)
--------------------------------------------------------------------------------

         reasonable discretion to appropriately adjust RCG's discounts for the
         relevant periods, by including or excluding any purchases made by those
         Affiliates during any of those periods.

10.      TREATMENT OF DISCOUNTS. RCG agrees that it will properly disclose and
         account for any discount or other reduction in price earned hereunder,
         in whatever form, (i.e. pricing, discount, or incentive) in a way that
         complies with all applicable federal, state, and local laws and
         regulations, including without limitation, Section 1128B(b) of the
         Social Security Act and its implementing regulations. Section 1128B(b)
         requires that a provider of services will properly disclose and
         appropriately reflect the value of any discount or other reduction in
         price earned in the costs claimed or charges made by the provider under
         a federal health care program, as that term is defined in Section
         1128B(f). RCG also agrees that it will (a) claim the benefit of such
         discount received, in whatever form, in the fiscal year in which such
         discount was earned or the year after, (b) fully and accurately report
         the value of such discount in any cost reports filed under Title XVIII
         or Title XIX of the Social Security Act, or a state health care
         program, and (c) provide, upon request by the U.S. Department of Health
         and Human Services or a state agency or any other federally funded
         state health care program, the information furnished by Amgen
         concerning the amount or value of such discount. RCG's corporate
         headquarters agrees that it will advise all Affiliates, in writing, of
         any discount received by RCG's corporate headquarters hereunder with
         respect to purchases made by such Affiliates and that said Affiliates
         will account for any such discount in accordance with the above stated
         requirements.

11.      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 Products 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.

12.      BREACH OF AGREEMENT. If either party materially breaches this
         Agreement, then the other party may terminate this Agreement for breach
         upon thirty (30) days' advance written notice. Upon termination of this
         Agreement by Amgen in accordance with this Section 12, Amgen shall have
         no obligation to continue to offer the terms described herein or pay
         any further discounts to RCG.

13.      GOVERNING LAW. This Agreement shall be governed by the laws of the
         State of California and the parties hereby submit to the jurisdiction
         of the California courts, both state and federal.

14.      WARRANTIES. Each party represents and warrants to the other that this
         Agreement: (a) has been duly authorized, executed, and delivered by it,
         (b) constitutes a valid, legal, and binding agreement enforceable
         against it in accordance with the terms contained herein, and (c) does
         not conflict with or violate any of its other contractual obligations,
         expressed or implied, to which it is a party or by which it may be
         bound. The party executing this



                                      -3-
<PAGE>
                             AMENDMENT NO. 1 AGREEMENT NO. 200308361 (CONTINUED)
--------------------------------------------------------------------------------

         Agreement on behalf of RCG specifically warrants and represents to
         Amgen that he is authorized to execute this Agreement on behalf of and
         has the power to bind RCG and the Affiliates to the terms set forth in
         this Agreement. The party executing this Agreement on behalf of Amgen
         specifically warrants and represents to RCG that he is authorized to
         execute this Agreement on behalf of and has the power to bind Amgen to
         the terms set forth in this Agreement.

15.      NOTICES. Any notice or other communication required or permitted
         hereunder shall be in writing and shall be deemed given or made when
         delivered in person or when sent to the other party by first class
         mail, nationally recognized overnight delivery service or other means
         of written communication at the respective party's current address or
         at such other address as the party shall have furnished to the other in
         accordance with this provision.

16.      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,
         regulation, policy, program memorandum or other interpretation,
         modification or utilization guideline by any governmental payer that in
         any manner reforms, modifies, alters, restricts, or otherwise affects
         the pricing of or reimbursement available for Products, including but
         not limited to a reimbursement or use decision, by Centers for Medicare
         and Medicaid Services ("CMS") or one of its contractors (Carriers or
         Fiscal Intermediaries), Amgen may, in its sole discretion, upon thirty
         (30) days notice, (i) terminate this Agreement, (ii) modify any pricing
         or discount terms contained herein, or (iii) exclude any Affiliates
         from participating in this Agreement. Without limiting the foregoing,
         any change, modification or further clarification to the Medicare
         Modernization Act or any rules or regulations promulgated thereunder,
         or the Hematocrit Measurement Audit Program Memorandum that occurs
         subsequent to the Amended Date would specifically trigger the right to
         the termination or modification referenced herein. 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. In the event Amgen chooses
         to invoke the provisions contained in this Section 16(a), Amgen agrees
         to enter into good faith discussions pertaining to modification of the
         existing agreement or entering into a new agreement, as applicable.

         (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, provided that, if Amgen so terminates an
         incentive, RCG shall be entitled to terminate this Agreement upon
         thirty (30) days notice.



----------
* 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.



                                      -4-


<PAGE>
                             AMENDMENT NO. 1 AGREEMENT NO. 200308361 (CONTINUED)
--------------------------------------------------------------------------------

         (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 Healthcare Operations,
         Research, and Public Health analyses, and RCG's Healthcare Operations.
         Unless otherwise specifically defined in this Agreement, each
         capitalized term used in this Section 16(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.

17.      FORCE MAJEURE. Neither party will be liable for delays in performance
         or nonperformance of this Agreement or any covenant contained herein if
         such delay or nonperformance is a result of Acts of God, civil or
         military authority, civil disobedience, epidemics, terrorism, war,
         failure of carriers to furnish transportation, strike, lockout or other
         labor disturbances, inability to obtain material or equipment, or any
         other cause of like or different nature beyond the control of such
         party.

18.      RIGHT OF FIRST OFFER. RCG shall promptly notify Amgen in the event it
         receives a competing offer from any third party for the sale of
         products in the same therapeutic class as the Products. Amgen shall
         have the right in such event to have forty-five (45) days to respond to
         RCG with its own pricing terms relating to products.

19.      MISCELLANEOUS. No modification of this Agreement will be effective
         unless mutually agreed upon, made in writing, and executed by a duly
         authorized representative of each party, except as otherwise provided
         hereunder. Neither party may assign this Agreement to a third party
         without the prior written consent of the other party. This Agreement
         may be executed in one or more counterparts, each of which is deemed to
         be an original but all of which taken together constitute one and the
         same agreement.

         (a) Beginning *, RCG's * by all Affiliates listed on Appendix B on the
         Amended Date of this Agreement during any * of this Agreement shall *
         of the * by those same Affiliates for the * . RCG shall not be eligible
         to receive any rebates detailed in Appendix A of this Agreement for any
         * in the aggregate made during any * of this Agreement that * of the *
         by those same Affiliates in the *. Any of RCG's aggregate * of the * by
         those same Affiliates in the * may be approved and eligible to receive
         rebates detailed in Appendix A if *. Such determination must be
         approved by *. For purposes of determining the foregoing, during the
         period *, Products base sales during each applicable time period shall
         be derived using the *.

20.      ENTIRE AGREEMENT. This Agreement constitutes the entire understanding
         between the parties and supersedes all prior written or oral proposals,
         agreements, or commitments pertaining to the subject matter and periods
         of time covered herein.







----------
* 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.



                                      -5-

<PAGE>
                             AMENDMENT NO. 1 AGREEMENT NO. 200308361 (CONTINUED)
--------------------------------------------------------------------------------

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


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


AMGEN USA INC.                                RENAL CARE GROUP, INC.

Signature:         /s/ Fred Manak             Signature:     /s/ David M. Dill
              ---------------------------                  ---------------------
Print Name:          Fred Manak               Print Name:      David M. Dill
              ---------------------------                  ---------------------
Print Title:  Dir. U.S. Corporate Pricing     Print Title:      EVP and CFO
              ---------------------------                  ---------------------
Date:                 12/2/04                 Date:              12/1/2004
              ---------------------------                  ---------------------









                                      -6-

<PAGE>
                             AMENDMENT NO. 1 AGREEMENT NO. 200308361 (CONTINUED)
--------------------------------------------------------------------------------


SECTION 2.  AMENDMENT AND RESTATEMENT OF APPENDIX A: DISCOUNT PRICING,
SCHEDULE AND TERMS.
--------------------------------------------------------------------------------
APPENDIX A: *

                APPENDIX A: DISCOUNT PRICING, SCHEDULE, AND TERMS

1.       PRICING - ARANESP(R). RCG and Affiliates may purchase Aranesp(R)
         (darbepoetin alfa) through * at a * off of the prevailing *. Amgen
         reserves the right to change the * at any time. Resulting prices do not
         include *.

2.       PRICING - EPOGEN(R). RCG and Affiliates may purchase EPOGEN(R) (Epoetin
         alfa) directly from Amgen or through * at a *, subject to the terms and
         conditions of Section 3 below. Amgen reserves the right to change the *
         at any time. Resulting prices do not include *. All discounts earned in
         arrears hereunder (also known as "rebates"), through the Term of the
         Agreement, shall be calculated based upon*.

3.       REBATE/INCENTIVE QUALIFICATION REQUIREMENTS.

         (a) *: In order for RCG to be eligible to receive any rebates or
         incentives described in Section 4 and Section 7 of this Appendix A, RCG
         must satisfy the following qualification requirement. No more than *
         may have * during each * during the Term of this Agreement *. If this
         criteria is not met during any * of the Term of the Agreement, RCG will
         not qualify for any rebates described in Section 4 and Section 7 of
         this Appendix A during that *. Failure of RCG to qualify under this
         provision during a particular *. The * for each dialysis patient will
         be based upon the average of all * for each patient during each *. RCG
         and Affiliates must provide the following information for each dialysis
         patient to Amgen or to a data collection vendor specified by Amgen, on
         a *, and no later than * after *: all * for each dialysis patient, the
         date of each *, and a consistent, unique, alpha-numeric 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. To the
         extent permitted by applicable law, Amgen may utilize the data detailed
         in this provision for any purpose, and reserves the right to audit all
         such data. Under no circumstances should such 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
         automated * method *, must be reported to *, and must be submitted
         directly from the clinical laboratory in a format acceptable to Amgen.
         Handwritten reports are not acceptable; only machine readable
         submission of the data will be accepted; and

         (b) *: In order for RCG to be eligible to receive any rebates or
         incentives described in Section 7 of this Appendix A, RCG must satisfy
         the following qualification requirement. RCG's * of EPOGEN(R) and
         Aranesp(R) during * and during * by all Affiliates listed on Appendix B
         on the Commencement Date of this Agreement and those added at the
         beginning of * must equal or exceed * and * respectively *, of the * of
         EPOGEN(R) and Aranesp(R) by those same Affiliates for the time period
         from *, for *, and from * for *. For purposes of calculating the *,
         EPOGEN(R) and Aranesp(R) base sales during each applicable time period
         shall be derived using the * in effect at the Commencement Date. All
         estimated payments for discounts in arrears that contain growth
         requirements will be measured by using a *. If RCG has not satisfied
         the * for any particular *, then *. The determination as to RCG's
         attainment or failure to attain the * shall be based upon the * in
         effect on the Commencement Date.

4.       *. RCG may qualify for the * during each * (as defined in the schedule
         below) as described in this Section 4 of Appendix A.





----------
* 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.



                                      -7-
<PAGE>
                             AMENDMENT NO. 1 AGREEMENT NO. 200308361 (CONTINUED)
--------------------------------------------------------------------------------

         (a) REQUIREMENT: In order to qualify for the * RCG must meet the *
         contained in Section 3(a) of this Appendix A. If this criteria is not
         met during any * during the period *, RCG will not qualify for *
         described below in this Section 4 during that *.

         (b) CALCULATION: RCG's * will be calculated in accordance with the
         following formula and the * listed below. * will be calculated on a *.

         (c) * . The * schedule is as follows:

         (d) PAYMENT. Estimated payments will be made * using *.

         (e) VESTING. RCG's * will vest at *.

5.       PARTNER INFORMATION PROGRAM *. For the Term of the Agreement RCG shall
         be eligible to receive a * provided certain data elements are
         transmitted to Amgen electronically. The * will be calculated as * of
         EPOGEN(R) attributable to RCG during each *. To qualify for the *, the
         following * must be submitted to Amgen by RCG and all Affiliates * :
         *
         (a) For the period *, the following * shall be added as requirements of
         the *:
         *
         (b) For the period *, the following * shall be removed a
         requirement of the *: *
         Such * must be submitted, on a *, and no later than * after *. If such
         * is received more than * after *, the * of EPOGEN(R) attributable to
         RCG during such * will be excluded from the calculation of the * for
         that * . Notwithstanding the foregoing, if Amgen receives all required
         * from * within the time frame referenced above for any * within a
         given *, the * of EPOGEN(R) attributable to RCG and all Affiliates
         during such *, will be included in the calculation of the * for that *.

6.       *. The purpose of the * is to improve the transmission, quality and
         validation of all data sent from RCG and its Affiliates and received by
         Amgen, such that the processes used by both companies are more
         efficient and timely. For the period * RCG shall be eligible to receive
         a * provided the following requirements below are met. The * will be
         calculated as * of EPOGEN(R) attributable to RCG during each *.

         (a) To qualify for * for the period *, the following requirements must
         be met:

                  i)       RCG must *;
                  ii)      RCG must *.


         (b) To qualify for the * for the period * , the following additional
         requirements must be met:

                  i)       RCG must *;
                  ii)      RCG and Amgen must mutually agree upon *:

                           o        *;
                           o        *;



----------
* 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.



                                      -8-

<PAGE>
                             AMENDMENT NO. 1 AGREEMENT NO. 200308361 (CONTINUED)
--------------------------------------------------------------------------------

                           o        *;
                           o        *;
                           o        *;
                           o        *;
                           o        *.
                           o        *.

         (c) To qualify for * for the period *, RCG must additionally achieve
         the * goals as set forth in *.

         The * referenced in this Section 6(a)(i) must be submitted, on *, and
         no later than * after *. If such * is received more than * after *, the
         * of EPOGEN(R) attributable to RCG during such * will be excluded from
         the calculation of the * for that *.

         The * will vest * on the * and be paid * in accordance with the terms
         and conditions described above.

7.       *. For the Term of the Agreement, RCG may qualify for the * provided it
         meets the criteria described below in this Section 7. The * is designed
         to improve patient outcomes by encouraging an increase in the number of
         patients managed within both the * set forth in the * which recommends
         a target * and a *.

         (a) Requirements: In order to qualify for the * , RCG must meet the
         Rebate/Incentive Qualification Requirements contained in Section 3 of
         this Appendix A, and RCG and its Affiliates must provide Amgen the
         following data items, on a * , and no later than * after *, in a * . In
         the event * is submitted, instead of *, Amgen will convert such * to *
         by *. Amgen will convert all * for each patient by RCG and its
         Affiliates, AND all the * for each patient by RCG and its Affiliates
         into the * for each patient by RCG and its Affiliates, AND the * for
         each patient by RCG and its Affiliates for each of the * (as defined in
         the schedule immediately below). RCG hereby certifies that the *
         submitted for each eligible Affiliate includes the required results
         from all dialysis patients of such Affiliate, and does not include
         results from non-patients. RCG 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 *.

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                ----------------------------------------------------------------
                                             *
                ----------------------------------------------------------------
                                             *
                ----------------------------------------------------------------
                                             *
                ----------------------------------------------------------------
                                             *
                ----------------------------------------------------------------

         (b) Calculation: Assuming RCG and Affiliates have fulfilled all
         requirements as described in Section 7(a) above, to qualify for the *,
         RCG must achieve an increase in the *, as that term is defined below,
         from the *, as that term is defined below, during each *, and such
         increase shall be defined as *.

         For purposes of this Section 7, * shall mean * for each patient by RCG
         and its Affiliates AND the * for each patient by RCG and its Affiliates
         during the period *; and * shall mean * for each patient by RCG and its
         Affiliates AND * for each patient by RCG and its Affiliates for each of
         the above referenced *.





----------
* 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.



                                      -9-
<PAGE>
                             AMENDMENT NO. 1 AGREEMENT NO. 200308361 (CONTINUED)
--------------------------------------------------------------------------------

         Using the * described above, the * will be calculated as the *, as
         shown below:

                                            *
                                            *
            --------------------------------------------------------------------
                                            *

         Using the * described above, which shall be calculated on a *, the *
         for each * will be calculated as the *, as shown below:

                                            *

                                            *
            --------------------------------------------------------------------
                                            *



         The * shall then be calculated by *, as shown below:

                                            *

         The * will be calculated on a * in accordance with *. Following
         determination of the *, Amgen shall then calculate RCG's * in
         accordance with the following formula and the * listed below:

                                            *
--------------------------------------------------------------------------------
            *                          *                            *
--------------------------------------------------------------------------------
            *                          *                            *
--------------------------------------------------------------------------------
            *                          *                            *
--------------------------------------------------------------------------------
            *                          *                            *
--------------------------------------------------------------------------------
            *                          *                            *
--------------------------------------------------------------------------------
            *                          *                            *
--------------------------------------------------------------------------------

                                            *
--------------------------------------------------------------------------------
            *                          *                            *
--------------------------------------------------------------------------------
            *                          *                            *
--------------------------------------------------------------------------------
            *                          *                            *
--------------------------------------------------------------------------------
            *                          *                            *
--------------------------------------------------------------------------------
            *                          *                            *
--------------------------------------------------------------------------------
            *                          *                            *
--------------------------------------------------------------------------------

                                            *
                                            *
--------------------------------------------------------------------------------
            *                          *                            *
--------------------------------------------------------------------------------
            *                          *                            *
--------------------------------------------------------------------------------
            *                          *                            *
--------------------------------------------------------------------------------
            *                          *                            *
--------------------------------------------------------------------------------



----------
* 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.


                                      -10-

<PAGE>
                             AMENDMENT NO. 1 AGREEMENT NO. 200308361 (CONTINUED)
--------------------------------------------------------------------------------


--------------------------------------------------------------------------------
            *                          *                            *
--------------------------------------------------------------------------------
            *                          *                            *
--------------------------------------------------------------------------------

         (c) Payment: The * will be calculated and paid to RCG on a *. Payment
         is contingent upon *. Such * must be submitted, on a *, and no later
         than * after *. If such * is received more than * after * within a
         given *, the * of EPOGEN(R) attributable to RCG during such * will be
         excluded from the calculation of the *. Notwithstanding the foregoing,
         if Amgen receives all required * from * within the time frame
         referenced above for any * within a *, the * of EPOGEN(R) attributable
         to RCG and all Affiliates during such *, will be included in the
         calculation of the *. However, if Amgen determines that any Affiliate
         is consistently not submitting the required *

         The * will vest * on the * and * respectively, and be paid * in
         accordance with the terms and conditions described above.

8.       * . For the period *, RCG may qualify for * as outlined below.

         (a) Calculation: *

         (b) Payment and Vesting: The * will vest on the * and will be paid
         within * after *.










----------
* 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.




                                      -11-
<PAGE>
                             AMENDMENT NO. 1 AGREEMENT NO. 200308361 (CONTINUED)
--------------------------------------------------------------------------------


                       APPENDIX B: LIST OF RCG AFFILIATES

(To be provided by RCG)






















                                      -12-
<PAGE>
                             AMENDMENT NO. 1 AGREEMENT NO. 200308361 (CONTINUED)
--------------------------------------------------------------------------------


                         APPENDIX C: LIST OF WHOLESALERS

TO ENSURE RCG RECEIVES THE APPROPRIATE DISCOUNT, IT IS IMPORTANT AMGEN RECEIVES
RCG'S CURRENT LIST OF AUTHORIZED WHOLESALERS. THE FOLLOWING LIST REPRESENTS THE
WHOLESALERS AMGEN CURRENTLY HAS ASSOCIATED WITH RCG'S CONTRACT. PLEASE UPDATE
THE LIST BY ADDING OR DELETING WHOLESALERS AS NECESSARY.










                                      -13-