<PAGE>   1
                                                                   EXHIBIT 10.33


   [AMGEN LOGO]      AMENDMENT #3 DATED JANUARY 30, 2001 TO AGREEMENT NO. 980202
--------------------------------------------------------------------------------

Agreement No. 980202, between Amgen Inc. ("Amgen") and Renal Care Group, Inc.,
including any prior amendments thereto, shall be amended and for the period
commencing April 1, 2001 shall be restated in its entirety to read as stated
below.

This agreement ("Agreement") together with all Appendices attached hereto and
incorporated herein by this reference, between Amgen Inc. ("Amgen") and Renal
Care Group, Inc., including the freestanding dialysis center affiliate(s) listed
on Appendix B (collectively, "Dialysis Center"), sets forth the terms and
conditions for the purchase of EPOGEN(R) (Epoetin alfa) by Dialysis Center for
the exclusive treatment of dialysis patients.

1.       TERM OF AGREEMENT. The "Term" of this Agreement shall be defined as
         April 1, 2001("Commencement Date") through December 31, 2001
         ("Termination Date").

2.       DIALYSIS CENTER AFFILIATES. Dialysis Center must provide Amgen with a
         complete list of its dialysis center affiliates ("Affiliates") on or
         before the date this Agreement is executed by Dialysis Center. Only
         those Affiliates approved by Amgen and referenced in Appendix B will be
         eligible to participate under this Agreement. Modifications to the
         dialysis center Affiliates listed on Appendix B may be made pursuant to
         the request of Dialysis Center's corporate headquarters and are subject
         to approval and acknowledgment by Amgen in writing. In order to allow
         Amgen the appropriate time to undergo through such approval process and
         to provide the Authorized Wholesalers (as defined below in Section 4)
         with the appropriate lead time to set up and account for any addition
         or deletion of Affiliates, Amgen requires no less than 30 days' notice
         before the effective date of change for any addition or deletion of
         Affiliates hereunder. Amgen reserves the right to accept, reject, or
         immediately terminate any Affiliates with regard to participation in
         this Agreement if Amgen determines that such Affiliate is not
         classified as a freestanding dialysis center or a home dialysis support
         facility.

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

4.       AUTHORIZED WHOLESALERS. Dialysis Center must provide Amgen with a
         complete list of its current wholesalers, from which Dialysis Center
         intends to purchase EPOGEN(R), and must provide the list to Amgen on or
         before the date this Agreement is executed by Dialysis Center's
         corporate headquarters. The list must include the name and complete
         address of each designated wholesaler. Wholesalers designated by
         Dialysis Center and approved by Amgen to participate in this program
         will be deemed "Authorized Wholesalers". A current listing of Dialysis
         Center's Authorized Wholesalers is referenced in Appendix B.
         Notification of proposed changes to the list of Authorized Wholesalers
         must be provided to Amgen in writing at least 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 Dialysis Center is purchasing
         EPOGEN(R), Amgen will work with Dialysis Center to identify other
         possible Authorized Wholesalers from which Dialysis Center may purchase
         EPOGEN(R) * Dialysis Center 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.

5.       QUALIFIED PURCHASES. Only EPOGEN(R)purchased under this Agreement by
         Dialysis Center through Authorized Wholesalers, at the contract prices
         set forth herein, as confirmed by Amgen based on sales tracking data,
         will be deemed "Qualified Purchases".

6.       COMMITMENT TO PURCHASE. Dialysis Center agrees to purchase EPOGEN(R)
         for all of its dialysis use requirements for recombinant human
         erythropoietin. Dialysis Center 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 Dialysis
         Center's corporate headquarters in writing that Amgen cannot supply
         EPOGEN(R) within and for the time period reasonably required by
         Dialysis Center.


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*        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. 980202                  -1-
<PAGE>   2

                                AMENDMENT #3 TO AGREEMENT NO. 980202 (CONTINUED)
--------------------------------------------------------------------------------


7.       CONFIDENTIALITY. Both Amgen and Dialysis Center 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.

8.       DISCOUNTS. Dialysis Center 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
         Dialysis Center's corporate headquarters. Discounts in arrears will be
         calculated in accordance with Amgen's discount calculation policies
         based on * using the * as the calculation price, except as otherwise
         provided hereunder. Upon vesting, Amgen will use its best efforts to
         make such discounts available within * after receipt by Amgen of data,
         in a form reasonably acceptable to Amgen, detailing all * during the
         applicable period. Payment amounts, as calculated by Amgen, must equal
         or exceed $100.00 for the applicable period to qualify. Subject to the
         section entitled "Breach of Agreement", in the event that Amgen is
         notified in writing that Dialysis Center, and/or any Affiliates (the
         "Acquiree") is acquired by another entity or a change of control
         otherwise occurs with respect to the Acquiree, any discounts which may
         have been earned hereunder shall be paid in the form of a check payable
         to the Acquiree'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 reasonable discretion to appropriately adjust Dialysis
         Center's discounts for the relevant periods, by including or excluding
         any purchases made by those Affiliates during any of those periods.

9.       TREATMENT OF DISCOUNTS. Dialysis Center 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). Dialysis Center 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. Dialysis
         Center's corporate headquarters agrees that it will advise all
         Affiliates, in writing, of any discount received by Dialysis Center'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.

10.      DATA COLLECTION. Dialysis Center agrees that all data to be provided to
         Amgen pursuant to this Agreement, shall be in a form that does not
         disclose the identity or name of any patient or other
         patient-identifying information such as address, telephone number, or
         social security number. Dialysis Center acknowledges that 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. Dialysis Center shall consistently use a unique
         alpha-numeric code (which shall not be the same as 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, Dialysis
         Center 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 that it will
         maintain data supplied under this Agreement in confidence and that it
         will not use such data to identify or contact any patient. No


----------

*        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. 980202                  -2-
<PAGE>   3

                                AMENDMENT #3 TO AGREEMENT NO. 980202 (CONTINUED)
--------------------------------------------------------------------------------


         reports by Amgen concerning analyses of the data or the results of such
         research shall disclose the identity of any patient.

11.      BREACH OF AGREEMENT. If either party materially breaches this
         Agreement, then the other party may terminate this Agreement for breach
         upon 30 days' advance written notice. In addition, in the event that
         Dialysis Center materially breaches any provision of this Agreement,
         Amgen shall have no obligation to continue to offer the terms described
         herein or pay any further discounts to Dialysis Center.

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

13.      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 Agreement on behalf of Dialysis Center
         specifically warrants and represents to Amgen that he is authorized to
         execute this Agreement on behalf of and has the power to bind Dialysis
         Center 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 Dialysis Center 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.

14.      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.

15.      COMPLIANCE WITH HEALTH CARE PRICING AND PATIENT PRIVACY LEGISLATION AND
         STATUTES. (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 adversely affects the pricing of or
         reimbursement available for EPOGEN(R), Amgen may, in its sole
         discretion, upon 30 days' notice (i) terminate this Agreement, or (ii)
         exclude any Affiliates from participating in this Agreement unless such
         Affiliate(s) certifies in writing that they are, or will be, exempt
         from the provisions thereunder. Additionally, in order to assure
         compliance with any existing federal, state or local statute,
         regulation or ordinance, Amgen reserves the right to exclude any
         Affiliates from the pricing, discount, and incentive provisions of this
         Agreement if, in the opinion of Amgen's legal counsel such exclusion is
         necessary to assure such compliance.

         (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 30 days' notice, seek to modify this Agreement with
         respect to the affected incentive. Dialysis Center 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 30 days' notice, provided that if Amgen so terminates an
         incentive, Dialysis Center shall be entitled to terminate this
         Agreement upon 30 days' notice.

16.      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



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*        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. 980202                  -3-
<PAGE>   4

                                AMENDMENT #3 TO AGREEMENT NO. 980202 (CONTINUED)
--------------------------------------------------------------------------------


         disobedience, epidemics, 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.

17.      MISCELLANEOUS. No modification of this Agreement will be effective
         unless 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 constitutes one and the same agreement.

18.      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 herein.


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 INC.                                RENAL CARE GROUP, INC.

Signature:                                Signature:
              ------------------------                  ------------------------
Print Name:                               Print Name:
              ------------------------                  ------------------------
Print Title:                              Print Title:
              ------------------------                  ------------------------
Date:                                     Date:
              ------------------------                  ------------------------


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*        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. 980202                  -4-
<PAGE>   5

                                AMENDMENT #3 TO AGREEMENT NO. 980202 (CONTINUED)
--------------------------------------------------------------------------------


                APPENDIX A: DISCOUNT PRICING, SCHEDULE, AND TERMS

1.       PRICING. Throughout the Term of this Agreement (April 1, 2001 -
         December 31, 2001), Dialysis Center may purchase EPOGEN(R) through * at
         an * which shall be equal to * . Amgen reserves the right to change the
         * at any time, which change shall * Dialysis Center during the Term of
         this Agreement. Resulting prices do not include * . All discounts
         earned in arrears during the Term of the Agreement shall be calculated
         based upon the *

2.       * . Dialysis Center may qualify for a * (" * ") provided it meets the
         criteria described below in this section. The * is designed to improve
         patient outcomes by encouraging * which recommends * .

         A.       REQUIREMENTS: In order to qualify for the * , Dialysis
                  Center's aggregate * of EPOGEN(R) by all Affiliates as listed
                  on Appendix B on the Commencement Date of this Agreement must
                  equal or exceed * of the aggregate * of EPOGEN(R) by those
                  same Affiliates for * . In addition, * Dialysis Center's * may
                  have * during * of the Term. If either of these criteria is
                  not met during * of the Term, Dialysis Center will not qualify
                  for the * during that * .

                  In order to participate in the * , Dialysis Center must
                  provide the following to Amgen or to a data collection vendor
                  specified by Amgen, on * , and * after the * :

         i)       all * for each dialysis patient, the date of each test, and a
                  consistent, unique, alpha-numeric identifier (sufficient
                  consistently to track an individual patient without in any way
                  disclosing the identity of the patient), 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, complete social security number, address or
                  birth date. The identity of the account submitting the Data
                  and any association with the Data will remain confidential.
                  The * test results must be derived from * taken immediately
                  before dialysis treatment using any * testing method * , must
                  be reported to the * , and must be submitted * in a format
                  reasonably acceptable to Amgen. Hand written reports are not
                  acceptable; electronic submission of the Data is preferred,
                  and

         ii)      a properly executed "Certification Letter", a sample of which
                  is attached hereto as Exhibit #1, that will be provided to
                  Dialysis Center's corporate headquarters, unless otherwise
                  requested, after this Agreement is executed by both parties.






          APPENDIX A: DISCOUNT PRICING, SCHEDULE, AND TERMS (CONTINUED)

         B.       CALCULATION: Assuming Dialysis Center has fulfilled all
                  requirements as described in Section 2(a) above, Dialysis
                  Center's * payment 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
                  Term. The * of all dialysis patients with * , will be
                  determined by dividing the total number of dialysis patients
                  with * by the total number of dialysis patients treated by
                  Dialysis Center. * will be calculated based on Dialysis
                  Center's overall performance in accordance with Amgen's
                  discount calculation policies.


----------

*        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. 980202                  -5-
<PAGE>   6

                                AMENDMENT #3 TO AGREEMENT NO. 980202 (CONTINUED)
--------------------------------------------------------------------------------


         C.       PAYMENT: The * will be calculated on * basis and paid to
                  Dialysis Center's corporate headquarters, except as otherwise
                  provided hereunder. Payment is contingent upon receipt by
                  Amgen of the "Certification Letter" and all required * for the
                  * . If Data is received more than * after * , the total * of
                  EPOGEN(R)attributable to Dialysis Center during * 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)from the calculation of the * for any * . *
                  payments will be based upon the Data received from the * , and
                  will equal a percentage of Dialysis Center's total * Purchases
                  of EPOGEN(R)during that * (exclusive of any * of EPOGEN(R)made
                  by Dialysis Center or any Affiliate not meeting the Data
                  submission requirements described above) as governed by the *
                  schedule listed below. *

                           *        OF ALL DIALYSIS PATIENTS *

                         WITH  *                      INCENTIVE PERCENTAGE

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

                                        *



         D.       VESTING: Dialysis Center's * will vest on * .




          APPENDIX A: DISCOUNT PRICING, SCHEDULE, AND TERMS (CONTINUED)

         E.       * SUBMISSION: In the event Dialysis Center adds any Affiliates
                  still submitting Data based on * to this Agreement, such
                  Affiliates' * of EPOGEN(R), for the * in which they were
                  added, shall be included in the calculation of the * payment.
                  Amgen will accept the * . In order for such added Affiliates'
                  * of EPOGEN(R) to be included in all subsequent * payment
                  calculations, such Affiliate must submit * .

3.       * DISCOUNT. Dialysis Center shall be eligible to receive a * if certain
         data elements are transmitted to Amgen electronically. The * will be
         calculated as a percentage of the * of EPOGEN(R) attributable to
         Dialysis Center during* . In order to qualify for the *, the following
         * must be submitted by all Affiliates * reasonably acceptable to Amgen
         * . Such * must be submitted, on * , and * . If such * are received *
         within * , the total * of EPOGEN(R) attributable to Dialysis Center * .
         * . However, if Amgen determines that any Affiliate is consistently not
         submitting the * , Amgen reserves the right in its sole discretion to
         exclude such Affiliate's * of EPOGEN(R) from the calculation of the *
         for * . * .

4.       * . Dialysis Center may qualify for the * ("*") as described below.

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


                                        *



----------

*        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. 980202                  -6-
<PAGE>   7
                                AMENDMENT #3 TO AGREEMENT NO. 980202 (CONTINUED)
--------------------------------------------------------------------------------




         *

         B.       VESTING: Dialysis Center's * will vest * .





















                 APPENDIX B: LIST OF DIALYSIS CENTER AFFILIATES

                                  See 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


----------

*        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. 980202                  -7-
<PAGE>   8

                                AMENDMENT #3 TO AGREEMENT NO. 980202 (CONTINUED)
--------------------------------------------------------------------------------


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

Henry Schein, Inc.
135 Duryea Road
Nelville, NY  11747

Priority HealthCare Corporation
285 West Central Parkway, Suite 1704
Altamonte Springs, FL  32714


























                           SAMPLE CERTIFICATION LETTER

                                                                      EXHIBIT #1






----------

*        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. 980202                  -8-
<PAGE>   9

                                AMENDMENT #3 TO AGREEMENT NO. 980202 (CONTINUED)
--------------------------------------------------------------------------------


Month X, 2001

FSDC Legal Name
Street Address
City, ST  Zip

RE:  EPOGEN(R) (Epoetin alfa) Agreement No. 9XXXXX

Dear ____________:

Thank you for your participation in the * Program. 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
incentive. If we do not receive the executed certification, we cannot provide
you with this incentive.

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 FSDC Legal Name and all eligible Affiliates participating in the *
Program under Agreement No. XXXXXX, 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. 980202                  -9-