<PAGE>
                                                                 EXHIBIT 10.19


                         Dialysis Organization Agreement
                                Information Sheet

 This Information Sheet sets forth certain definitions and other information as
 used in the attached Dialysis Organization Agreement. As used in such Dialysis
 Organization Agreement, the following terms shall have the meanings ascribed
 below:

 DIALYSIS CENTER (FULL LEGAL NAME): Renal Care Group, Inc.
                                    ----------------------
 TERRITORY: United States
            -------------
 TERM START DATE: January 1, 2006
                  ---------------
 TERM END DATE: December 31, 2007
                -----------------
 PRODUCTS: EPOGEN(R) (Epoetin alfa) and Aranespe (darbepoetin alfa)
           --------------------------------------------------------
 PRODUCT INVOICE DISCOUNT PERCENTAGES:

 PRODUCT: EPOGEN(R)                             INVOICE DISCOUNT PERCENTAGE:*%
          --------------------------------------
 PRODUCT: Aranesp(R)                            INVOICE DISCOUNT PERCENTAGE:*%
          --------------------------------------

DIALYSIS CENTER NOTICE ADDRESS AND FAX:
Renal Care Group, Inc.
2525 West End Avenue, Suite 600
Nashville, TN 37203
Fax: (615)345-5503
Attn: Senior Vice-President of Medical and Legislative Affairs


With a copy to:
Renal Care Group, Inc.
2525 West End Avenue, Suite 600
Nashville, TN 37203
Fax: (615) 345-5503
Attn: General Counsel


AMGEN AGREEMENT NO.: 200600024
                      ---------


----------
* 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>
                                                 Dialysis Organization Agreement


This Dialysis Organization Agreement (this "Agreement") is made by and between
Amgen USA Inc. ("Amgen") and Dialysis Center to set forth the terms and
conditions upon which Dialysis Center shall purchase Products and Amgen shall
pay rebates.

Amgen and Dialysis Center hereby agree as follows:

1.      DEFINITIONS

When used with initial capitals herein, the following terms shall have the
meanings ascribed to them below:

1.1.    "Affiliate" of a given entity shall mean an entity that controls, is
        controlled by, or under common control with such given entity. Control
        shall mean ownership of more than fifty percent (50%) of the voting
        stock of an entity or, for non-stock entities, the right to more than
        fifty percent (50%) of the profits of such entity.

1.2.    "Authorized Wholesalers" shall mean those wholesalers listed on Schedule
        1.2, as such list may be modified pursuant to Section 2.3.

1.3.    "Data" shall mean the data provided by Dialysis Center to Amgen
        hereunder in accordance with Article 4.

1.4.    "Designated Affiliates" shall mean any Affiliate of Dialysis Center
        listed on Schedule 1.4, as such list may be modified pursuant to Section
        2.2.

1.5.    "Dialysis Center" shall mean the company specified on the Information
        Sheet.

1.6.    "Invoice Discount Percentage" shall mean, with respect to a particular
        Product, the percentage set forth in the Information Sheet.

1.7.    "HIPAA" shall mean the Health Insurance Portability and Accountability
        Act of 1996 and its implementing regulations, each as amended.

1.8.    "Individually Identifiable Health Information" shall have the meaning
        specified in HIPAA.

1.9.    "Information Sheet" shall mean the information sheet attached hereto.

1.10.   "Managed Centers" shall mean an entity for which Dialysis Center
        provides management and administrative services including the purchase
        and billing of Products, and that is listed on Schedule 1. 10, as such
        list may be modified pursuant to Section 2.2.

1.11.   "Products" shall mean the Amgen products specified on the Information
        Sheet.

1.12.   *

1.13.   *

1.14.   *

----------
* 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.200600024                                  Ver. 1219/05 2 CMA 10866
                                       2
<PAGE>
2. PURCHASE AND SALE OF PRODUCTS

2.1.   Discounts. Dialysis Center, its Designated Affiliates and Managed Centers
       shall have the right to purchase Products through Authorized Wholesalers
       at * less the *. Amgen reserves the right to change Product list price at
       any time, by any amount, without notice; provided, however, that Amgen
       shall not increase the EPOGENO list price charged to Dialysis Center, its
       Designated Affiliates and Managed Centers by more than * percent (*%) in
       each * period during the term of this Agreement, except in the event of
       an unanticipated material change in applicable government reimbursement
       and/or coverage laws, regulations or policies for EPOGEN(R). Prices set
       forth in this Agreement are without regard to any wholesaler markup,
       service fees, or other charges, which may be charged separately by
       Authorized Wholesalers.

2.2.   Affiliates. Only purchases of Products made by Dialysis Center, its
       Designated Affiliates and Managed Centers shall be eligible
       for the pricing, discounts and rebates granted pursuant to this
       Agreement. Dialysis Center shall have the right to add its Affiliates to
       or from the list of Designated Affiliates and add Managed Centers to or
       from the list thereof by thirty (30) days prior written notice to Amgen
       upon Amgen's approval, which shall not be unreasonably withheld or
       delayed. In the event of a change to information regarding a Designated
       Affiliate or Managed Center (such as address), Dialysis Center shall
       promptly notify Amgen, and Amgen shall update the relevant list. Dialysis
       Center shall have the right to remove Affiliates of Dialysis Center from
       the list of Designated Affiliates and Managed Centers from the list
       thereof by thirty (30) days prior written notice to Amgen. In the event
       of any such removal, Amgen shall prorate any affected calculations and
       payments accordingly. Amgen reserves the right to accept, reject or
       immediately terminate any Designated Affiliate or Managed Center with
       regard to participation under this Agreement, if Amgen: (i) reasonably
       determines that such Designated Affiliate or Managed Center is not
       properly classified as a freestanding dialysis center or home dialysis
       support facility, (ii) has reasonable concerns regarding the security of
       such Designated Affiliate or Managed Center with respect to Products;
       (iii) has reasonable evidence that such Designated Affiliates or Managed
       Center has diverted Products to a person or entity that is not entitled
       to purchase Products under this Agreement; (iv) such Designated Affiliate
       or Managed Center or any of its employees is debarred or excluded from
       participation in the Medicare or Medicaid program and, if an employee,
       such employee is retained by his employer for more than five (5) business
       days after Amgen gives notice of such debarment or exclusion to Dialysis
       Center; or (v) determines that such Designated Affiliate or Managed
       Center is a party to another purchase agreement for EPOGEN(R) or Aranese
       with Amgen. Dialysis Center shall ensure compliance with the terms and
       conditions of this Agreement applying to Dialysis Center by its
       Designated Affiliates and Managed Centers. Dialysis Center shall be
       jointly and severally liable for the acts and omissions of its Affiliates
       and Managed Centers, and Amgen shall have the right (but not the
       obligation) to proceed directly against Dialysis Center in the event of a
       breach of this Agreement by any such Affiliate or Managed Center, without
       first proceeding against such Affiliate or Managed Center.

2.3.   Authorized Wholesalers. Only Products purchased from Authorized
       Wholesalers shall be eligible for the pricing, discounts and rebates
       granted pursuant to this Agreement. Dialysis Center shall have the right
       to remove wholesalers from the list of Authorized Wholesalers by thirty
       (30) days prior written notice to Amgen, and shall have the right to add
       wholesalers to the list of Authorized Wholesalers by thirty (30) days
       notice to Amgen upon Amgen's approval, which shall not be unreasonably
       withheld or delayed. Amgen shall have the right

----------
* 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.200600024                                  Ver. 1219/05 2 CMA 10866

                                        3
<PAGE>
       to add or remove wholesalers from the list of Authorized Wholesalers by
       thirty (30) days prior written notice to Dialysis Center. In the event of
       any such removal by Amgen, Amgen shall work with Dialysis Center to
       transition Dialysis Center's purchasing to an Authorized Wholesaler and
       shall use reasonable efforts to establish a direct purchasing
       relationship in any interim period between the removal of the removed
       Authorized Wholesaler and the initiation of purchases from a new
       Authorized Wholesaler, if no alternative Authorized Wholesaler exists at
       such time that can meet Dialysis Center's reasonable expected
       requirements of Products. Dialysis Center shall complete and submit to
       Amgen an application for direct ship account. Purchases made directly
       from Amgen shall be subject to reasonable credit limits established by
       Amgen (or the parties may agree on one or more methods (such as an
       irrevocable letter of credit) to assure Amgen of payment for any such
       Product).

2.4.   Own Use. Only Products purchased for Dialysis Center's, its Designated
       Affiliates' or its Managed Centers' "own use" for the treatment of
       dialysis patients shall be eligible for the pricing, discounts and
       rebates granted pursuant to this Agreement. Dialysis Center, its
       Designated Affiliates and its Managed Centers covenant that they shall
       not seek any such pricing, discounts or rebates for any Products that are
       not for its or their "own use" for the treatment of dialysis patients,
       and Dialysis Center shall promptly notify Amgen in the event Amgen does
       provide Dialysis Center, its Designated Affiliate or a Managed Center any
       such pricing, discount or rebates.

2.5.   Product License Agreement. Dialysis Center, its Designated Affiliates and
       its Managed Centers agree to respect that certain Product License
       Agreement between Amgen and Ortho Pharmaceutical Corporation as described
       in this Section 2.5. In accordance with the terms of the Product License
       Agreement, Amgen has the exclusive right to promote and sell Epoetin alfa
       in the United States under the trade name EPOGEN(R) for use with dialysis
       patients. Amgen has licensed Ortho, as Amgen's distributor, the exclusive
       right to promote and sell Epoetin alfa in the United States, under the
       trade name PROCRIT11, for non-dialysis uses only. Ortho sells and
       promotes Epoetin alfa in the United States under the trade name PROCRIr.
       PROCRIr is a registered trademark of Ortho Biotech Products, L.P. Ortho
       is not authorized to promote or sell PROCRIr in the United States for
       dialysis use. Dialysis Center, its Designated Affiliates and its Managed
       Centers agree to respect the unique marketing rights of Amgen and Ortho
       as set forth in the Product License Agreement, as described above.
       Consistent with the terms of the License Agreement, Dialysis Center, its
       Designated Affiliates and its Managed Centers shall use only EPOGEN(R) or
       Aranespo (and not PROCRIr) for patients undergoing dialysis.

2.6.   Vial Sizes. Dialysis Center acknowledges that Amgen has an interest in
       forecasting the vial size mix of purchases of Products in order to help
       Amgen in its efforts to provide uninterrupted supply of preferred vial
       sizes. Dialysis Center shall use commercially reasonable best efforts to
       give Amgen at least six months' prior written notice if it has reason to
       expect that the percentage of its purchases made up by any particular
       stock keeping unit (SKU) will deviate by more than *% from the previous
       calendar quarter.

3. REBATES

3.1.   Earninq and Vesting of Rebates. Dialysis Center shall qualify for rebates
       based upon its and its Designated Affiliates' and Managed Centers'
       verified * in accordance with the terms and conditions of this Agreement
       and the formulae set forth in Exhibit 3.1. For the purposes of
       calculations of rebates hereunder, purchases shall be deemed made on the
       date of invoice to the Dialysis Center (or Designated Affiliate and
       Managed Center) from the Authorized Wholesaler.

----------
* 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.200600024                                  Ver. 1219/05 2 CMA 10866

                                       4
<PAGE>
3.2.   Payment of Rebates. Rebates shall be paid quarterly in arrears by
       electronic funds transfer using EFT information provided to Amgen by
       Dialysis Center as necessary to enable EFT payment. Payment amounts must
       exceed $500.00 to qualify for payment; payment amounts of less than
       $500.00 at time of calculation will be carried over to the next payment
       period until such time as an aggregate amount equal to or greater that
       $500.00 is earned.

3.3.   Verification and Audit. Rebates specified herein are subject to
       verification and audit of the relevant purchase and other data (including
       Data supplied pursuant to Article 4), and such rebates are
       contingent upon Amgen's timely receipt of all relevant purchase data from
       Authorized Wholesalers, in a form reasonably acceptable to Amgen, as
       reasonably necessary to calculate amounts payable hereunder. Dialysis
       Center, its Affiliates and Managed Centers shall maintain its and their
       books and records in accordance with U.S. generally accepted accounting
       principles, consistently applied. Dialysis Center, its Affiliates and
       Managed Centers shall provide Amgen and its designee reasonable access at
       Dialysis Center's corporate headquarters to applicable books and records
       (which shall be limited to information regarding *, and any information
       necessary to verify and confirm payment pursuant to and compliance with
       this Agreement) in order to audit and assure compliance with the terms of
       this Agreement on five (5) business days written notice. Any such audit
       shall be conducted during normal business hours, and so as not to
       unreasonably interfere with the business of Dialysis Center, its
       Affiliates or Managed Centers. Dialysis Center shall ensure that all
       books and records requested by Amgen for such purposes are made available
       to Amgen at Dialysis Center's corporate headquarters. In the event any
       such audit shows that Dialysis Center, its Affiliate or Managed Center
       has submitted incorrect information resulting in Dialysis Center
       receiving in excess of 110% of the amount to which it was entitled in any
       calendar quarter, Dialysis Center shall reimburse Amgen the reasonable
       costs of such audit. Following any audit that shows any over or
       underpayment hereunder, the relevant party shall, within sixty (60) days,
       make payment to the other party for the difference between the amount
       paid hereunder and the amount actually payable hereunder based upon the
       results of such audit.

3.4.   Adjustments for Changes. In the event of the addition or deletion of any
       Designated Affiliates or Managed Center during any calendar quarter of
       the term of this Agreement, Amgen shall adjust * to account for such
       change by adding or deleting such Designated Affiliates' or Managed
       Center's purchases to or from the relevant quarter or comparison quarter
       (or portion thereof).

3.5.   Treatment of Discounts and Rebates. Dialysis Center agrees that it, its
       Designated Affiliates and Managed Centers shall properly disclose and
       account for all discounts and rebates earned hereunder, in whatever form,
       in compliance with all applicable federal, state, and local laws and
       regulations, including Section 1 12813(b) of the Social Security Act and
       its implementing regulations. Dialysis Center also agrees that it, its
       Designated Affiliates and Managed Centers shall (i) claim the benefit of
       such discount or rebate received in the fiscal year in which such
       discount or rebate was earned or the year after, (ii) fully and
       accurately report the value of such discount or rebate in any cost
       reports filed under Title XVIII or Title XIX of the Social Security Act,
       or a state health care program, and (iii) 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 to Dialysis Center, its Designated Affiliates or Managed
       Centers by Amgen concerning the amount or value of such discount or
       rebate.

3.6.   Reports. Amgen shall provide to Dialysis Center a quarterly statement of
       the rebates earned hereunder with the itemization of Product
       purchases made in a particular calendar quarter, broken down by
       Designated Affiliates and Managed Centers; and any other information that
       Dialysis Center may reasonably request that is reasonably available to
       Amgen. Dialysis Center agrees that it will provide such information to
       its Designated Affiliates and Managed Centers in a timely manner in order
       to allow such

----------
* 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.200600024                                  Ver. 1219/05 2 CMA 10866
                                       5
<PAGE>
       Designated Affiliates and Managed Centers to meet their reporting and
       other obligations hereunder and under applicable law and regulation.

4. PRODUCT DATA

4.1.   Data Submission. Dialysis Center shall provide the Data specified in
       Exhibit 3.1 to Amgen (or to a data collection vendor specified by Amgen)
       within thirty (30) days of the end of each calendar month. Such Data
       shall be provided in the format set forth in such Exhibit.

4.2.   HIPAA Compliance. Dialysis Center shall not provide Amgen (or any
       specified data collection vendor) any Data in violation of HIPAA. Any
       Individually Identifiable Health Information shall have been
       de-identified in accordance with HIPAA prior to provision to Amgen or its
       designee.

4.3.   Case Identifier. Dialysis Center shall consistently use a unique
       alpha-numeric code (which shall not be derived from Individually
       Identifiable Health Information) 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. Dialysis Center will not
       provide to Amgen the key or list matching patient identities to their
       unique case identifiers.

4.4.   Data Use. Amgen shall have the right to use Data to support verification
       of the services referenced in this Agreement, for Amgen-sponsored
       research and analysis, development of marketing materials, running
       internal trending analyses, overall analyses of how to improve treatment
       of patients on dialysis, creating tools by Amgen marketing personnel, and
       other Amgen business purposes. Notwithstanding the foregoing, without
       Dialysis Center's prior written consent (such consent not to be
       unreasonably withheld or delayed): (i) Amgen shall not disclose to third
       parties the health information data provided by Dialysis Center hereunder
       except pursuant to public health activities as required by law or
       regulation and to agents of Amgen bound by commercially reasonable
       obligations of confidentiality (or as required by law or regulation),
       Amgen agreeing that it will be liable for any breach of such
       confidentiality obligations by such agents; and (ii) Amgen shall not sell
       or resell any such data or derivative works thereof to any third party.

5. WARRANTIES, REPRESENTATIONS AND COVENANTS

5.1.   Power and Authority. 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 or she is
       authorized to execute this Agreement on behalf of and has the power to
       bind Dialysis Center, its Affiliates and Managed Centers 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 or
       she is authorized to execute this Agreement on behalf of and has the
       power to bind Amgen.

5.2.   Compliance with Law and Regulation. Amgen shall, and Dialysis Center, its
       Affiliates and Managed Centers shall, comply with all applicable laws and
       regulations.

5.3.   Products. Amgen warrants that, as of the time of delivery by Amgen to a
       common carrier or other third party that:

       5.3.1. the Products are not adulterated or misbranded (as such terms are
              described in the Federal Food Drug and Cosmetic Act) or a product
              that may not be introduced into interstate commerce;

       5.3.2. that the Products are as described in their labeling; and

       5.3.3. the Products have been manufactured in accordance with cGMPs.

Agreement No.200600024                                  Ver. 1219/05 2 CMA 10866
                                       6
<PAGE>
5.4.   NO OTHER WARRANTIES. OTHER THAN THE WARRANTIES EXPRESSLY SET FORTH
       HEREIN, NEITHER PARTY MAKES, AND EACH PARTY EXPRESSLY DISCLAIMS, ALL
       OTHER WARRANTIES, INCLUDING THOSE OF MERCHANTABILITY AND FITNESS FOR A
       PARTICULAR PURPOSE.

6. INDEMNITY

6.1.   [INTENTIONALLY OMITTED]

6.2.   Indemnity.

       6.2.1. By Amgen. Amgen agrees to indemnify, defend and hold harmless
              Dialysis Center, its Affiliates and Managed Centers, and its and
              their respective employees, officers and directors from and
              against any and all amounts payable to third parties pursuant to a
              written settlement agreement or court order ("Third Party Awards")
              incurred by Dialysis Center, its Affiliates and Managed Centers
              that result directly from: (a) Products that as of the date of
              shipment by Amgen: (i) contain defects in material and
              workmanship, (ii) are adulterated or misbranded within the meaning
              of applicable provisions of the FDC Act, or (iii) are prohibited
              from being introduced into interstate commerce by Section 301 of
              the FDC Act or Section 351 of the Public Health Service Act, or
              (b) Amgen's gross negligence or willful misconduct or breach of
              this Agreement, which breach remains uncured for thirty (30) days
              after Dialysis Center gives Amgen notice of such breach; or (c)
              Products that infringe any patent or other intellectual property
              right of any person when used for the treatment of anemia in
              dialysis patients in accordance with the labeling for such
              Product; and reasonable out of pocket payments incurred by
              dialysis center Dialysis Center, its Affiliates and Managed
              Centers, and its and their respective employees, officers and
              directors in the response to any matter described in (a), (b) or
              (c) above ("Expenses"); provided that the indemnity contemplated
              by this Section 6.2.1 shall not apply to Third Party Awards and
              Expenses arising out of the negligent or willful actions or
              omissions of Dialysis Center, its Affiliates or Managed Centers,
              or its or their respective agents, employees, representatives,
              successors or assigns, or to the extent they arise out of a matter
              for which Dialysis Center is required to indemnify Amgen pursuant
              to Section 6.2.2 of this Agreement, or due to defects in the
              Products caused by persons other than Amgen or that result from
              neglect, misuse, unauthorized adulteration or modification,
              improper testing, handling or storage or any cause beyond the
              range of normal usage; and further provided that (x) Amgen is
              promptly notified in writing of any such third party claim for
              which this indemnity obligation may apply, (y) Amgen shall have
              sole control of the defense and settlement thereof, and (z)
              Dialysis Center cooperates fully and gives Amgen all requested
              information and assistance for such defense. The preceding
              paragraph sets forth Dialysis Center's and its Affiliates' sole
              remedy for claims of Product defect, adulteration, infringement or
              misbranding.

       6.2.2. By Dialysis Center. Dialysis Center, its Affiliates and Managed
              Centers agree to indemnify, defend and hold harmless Amgen and its
              respective employees, officers and directors from and against any
              and all Third Party Awards and Expenses that result from Dialysis
              Center's, its Affiliates' or its Managed Centers' transportation,
              handling, storage, promotion or sale of the Products and not
              arising solely out of Amgen's negligence, or a matter for which
              Amgen is required to indemnify Dialysis Center pursuant to the
              above paragraph; provided, however, that (a) Dialysis Center is
              promptly notified in writing of any such third party claim for
              which this indemnity obligation may apply, (b) Dialysis Center
              shall have sole control of the defense and settlement thereof, and
              (c) Amgen cooperates fully and gives Dialysis Center all requested
              information and assistance for such defense.


       6.2.3. NO INCIDENTAL OR CONSEQUENTIAL DAMAGES. NEITHER PARTY SHALL HAVE
              THE OBLIGATION TO INDEMNIFY THE OTHER PURSUANT TO THIS

Agreement No.200600024                                 Ver. 1219/05 2 CMA 10866
                                       7
<PAGE>
              SECTION 6.2 FOR ANY INCIDENTAL OR CONSEQUENTIAL DAMAGES,
              (INCLUDING ANY LOSS OF SALES, PROFITS, OR OPPORTUNITY) REGARDLESS
              OF WHETHER SUCH PARTY HAS BEEN ADVISED OF OR IS OTHERWISE AWARE OF
              THE POSSIBILITY OF SUCH DAMAGES.

7.   TERM AND TERMINATION

7.1.   Term. This Agreement shall come into effect as of the Term Start Date and
       shall expire as of the Term End Date, unless sooner terminated in
       accordance with this Article 7.

7.2    Termination. Either party may terminate this Agreement in the event of an
       uncured material breach following thirty (30) days written notice of same
       (which termination shall be automatically effective at the end of such
       thirty (30) day period should such breach remain uncured). In addition,
       Amgen shall have the right to terminate this Agreement in the event of
       material commercial or regulatory change by written notice to Dialysis
       Center. Amgen shall provide as much prior written notice of any such
       termination as practicable (but not less than thirty (30) days prior
       written notice). Immediately following the giving of such notice by
       Amgen, Amgen and Dialysis Center shall each use diligent efforts to
       negotiate a replacement agreement for this Agreement to be effective as
       of the termination hereof.

7.3.   Compliance with or Change in Law or Regulation. Notwithstanding anything
       contained herein to the contrary, in order to assure compliance with any
       existing federal, state or local statute, regulation or ordinance, or 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 materially reforms, modifies, alters, restricts, or otherwise
       affects the pricing of or reimbursement available for any of the
       Products, including but not limited to the enactment of any reimbursement
       rule, guideline, final program memorandum, coverage decision, pricing
       decision, instruction or the like by the Centers for Medicare and
       Medicaid Services ("CMS") or one of its contractors (carriers or fiscal
       intermediaries), or any material change in reimbursement systems that in
       any manner reforms, modifies, alters, restricts or otherwise affects the
       reimbursement available to Dialysis Center for any of the Products, upon
       ten (10) days prior written notice, (i) subject to the limitations set
       forth in Section 2.1 above, Amgen may, in its sole discretion, modify any
       pricing, rebate or discount terms contained herein, or (ii) Amgen may, in
       its reasonable discretion applied solely to address such law or change in
       law, exclude any Designated Affiliates or Managed Centers from
       participating in this Agreement. Without limiting the foregoing, any
       material change, modification or further clarification to the Medicare
       Prescription Drug Improvement and Modernization Act of 2003 ("MMA") or
       any rules or regulations promulgated there under, or the Erythropoietin
       Monitoring Policy for ESRD Patients that occurs subsequent to the Term
       Start Date would specifically trigger the right to modify referenced
       herein. Additionally, to assure compliance with any existing federal,
       state or local statute, regulation or ordinance, Amgen reserves the
       right, in its reasonable discretion, to exclude any Designated Affiliates
       or Managed Centers from the pricing, rebate and discount provisions of
       this Agreement.

7.4.   Effect of Merger. Amgen acknowledges that Dialysis Center is a party to
       an Agreement, dated May 4, 2005, under which Dialysis Center has agreed
       to be acquired by Fresenius Medical Care AG (the "Merger Agreement").
       Amgen and Dialysis center agree that, following the closing of such
       transaction (the "Merger"), Amgen and Dialysis Center shall work together
       to transition all purchases of Product by Dialysis Center, its Designated
       Affiliates and Managed Centers to Fresenuis' Dialysis Organization
       Agreement with Amgen. Within thirty (30) days after the Merger (or by
       such other later date that the parties shall agree in writing), all such
       purchases shall be made under Fresenuis' Dialysis Organization Agreement
       with Amgen. Amgen shall vest any unvested rebates and pay the same within
       ninety (90) days after the last day of the month in which the last
       purchase of Products is made, provided Amgen is in

Agreement No.200600024                                  Ver. 1219/05 2 CMA 10866
                                        8
<PAGE>
       timely receipt of all data in the form required by this Agreement.

7.5.   Effect of Termination. Upon any termination or expiration of this
       Agreement, any earned and vested rebates shall be paid in accordance with
       the terms set forth in Article 3. Upon termination of this Agreement for
       any reason other than actual or threatened breach by Dialysis Center, any
       earned but unvested rebates shall vest as of the effective date of such
       termination. In the event of any termination during a calendar quarter,
       Amgen shall pro-rate any data used in calculating payments hereunder, and
       such payments, as appropriate.

7.6.   Survival. The following provisions shall survive any expiration or
       termination of this Agreement: Sections 3.2 - 3.5 (with respect to
       periods prior to such expiration or termination) and 7.5 and Articles 4
       (with respect to periods prior to such expiration or termination), 6
       and 8.

8. MISCELLANEOUS

8.1.   Amendment. Except as expressly set forth herein, no amendment of this
       Agreement shall be effective unless expressed in a writing signed by each
       of the parties.

8.2.   Assignment. Neither party shall have the right to assign this Agreement
       without the other's prior written consent, and any attempted assignment
       shall be void. Notwithstanding the foregoing, Amgen shall have the right
       to assign this Agreement, in its entirety, to an Affiliate. This
       Agreement shall be binding on the parties' permitted successors and
       assigns.

8.3.   Conflicting Provisions. In the event of any conflict between this
       Agreement and any purchase order or invoice relating to the subject
       matter of this Agreement, including service fees, purchase orders or
       payment terms, this Agreement shall control.

8.4.   Construction. This Agreement shall be deemed to have been jointly drafted
       by the parties and no rule of strict construction shall
       apply against either party. As used herein, the word "including" shall
       mean "including, without limitation."

8.5.   Counterparts. This Agreement may be executed in one or more counterparts,
       each of which shall be considered an original.

8.6.   Currency. All amounts herein are set forth in United States Dollars.

8.7.   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, war, failure of carriers to
       furnish transportation, strike or other labor disturbances, inability to
       obtain material or equipment, or any other cause of like nature beyond
       the control of such party.

8.8.   Further Assurances. Each party shall perform all further acts reasonably
       requested by the other party to effectuate the purposes of this
       Agreement.

8.9.   Governing Law. This Agreement shall be governed by the laws of the State
       of California, excluding its choice of law rules. Solely for purposes of
       resolving disputes under this Agreement, each party hereby irrevocably
       submits to the jurisdiction of the state and Federal courts located in
       the State of California, and agrees that any dispute arising out of or
       relating to this Agreement shall be heard in a state or Federal court
       located in Los Angeles county, California, and agrees that it shall not
       assert any objection or defense of lack of jurisdiction, improper venue
       or forum non conveniens in any dispute brought in such courts. The
       parties agree that any such dispute shall be adjudicated as between the
       parties, and neither party shall seek certification as a class.
       Notwithstanding the foregoing, either party shall have the right to join
       any party ruled indispensable by the relevant court.

8.10.  Merger. This Agreement, together with the Information Sheet, constitutes
       the entire Agreement, written or oral, of the parties concerning the
       subject matter hereof. The

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<PAGE>
       Exhibits to this Agreement are hereby incorporated into and made a part
       of this Agreement. This Agreement supersedes any prior or contemporaneous
       agreements on the subject matter hereof, including any prior data use
       agreement between the parties.

8.11.  No Partnership. The relationship between Amgen and Dialysis Center, its
       Affiliates and Managed Centers is that of independent contractors, and
       not a partnership or an agency, franchise or other relationship. Neither
       party shall have the authority to bind the other.

8.12.  Notices. Any notice or other communication required or permitted
       hereunder shall be in writing and shall be deemed given or made five (5)
       days after deposit in the United States mail with proper postage for
       first-class registered or certified mail prepaid, return receipt
       requested, or when delivered personally or by facsimile (as shown by
       concurrent written transmission confirmation), or one (1) day following
       traceable delivery to a nationally recognized overnight delivery service
       with instructions for overnight delivery, in each case addressed to the
       address set forth for Amgen below, or for Dialysis Center, at the address
       set forth in the Information Sheet, or at such designated address that
       either party shall have furnished to the other in accordance with this
       Section 8.12:

       If to Amgen:
                          Amgen USA Inc.
                          One Amgen Center Drive, M/S 37-2-B
                          Thousand Oaks, CA 91320-1789
                          Attn: Sr. Contract and Pricing Analyst -
                                Nephrology Business Unit
                          Fax: (805) 376-8558

       with a copy to:    Amgen USA Inc.
                          One Amgen Center Drive, M/S 28-2-D
                          Thousand Oaks, CA 91320-1789
                          Attn: General Counsel
                          Fax: (805) 499-8011


8.13.  Publicity. The terms and conditions of this Agreement and the amount and
       structures of any discount, rebate or other reduction in price described
       herein are the confidential information of the parties, and neither party
       shall disclose the same to any person or entity without the other's prior
       written consent, except as necessary to comply with obligations pursuant
       to Section 3.5 or applicable law or regulation. Dialysis Center shall
       only share such information with those employees who have a need to know
       and shall only use such information for the purpose of fulfilling its
       obligations under this Agreement. Neither party shall make any press
       release in connection with the execution of this Agreement without the
       other party's prior written consent.

8.14.  Severability. Should any one or more of the provisions of this Agreement
       be determined to be illegal or unenforceable, the parties shall attempt,
       in good faith, to negotiate a modification of this Agreement so as to
       comply with the relevant law or regulation. Should they be unable to do
       so within thirty (30) days, either party shall have the right to
       terminate this Agreement upon ten (10) days prior written notice to the
       other.

8.15.  Waiver. No party shall be deemed to have waived any right hereunder,
       unless such waiver is expressed in a writing signed by such party.

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                                       10
<PAGE>
The parties have executed this Agreement by their designated representatives set
forth below.


AMGEN USA INC.                             RENAL CARE GROUP, INC.



By: /s/ Fred Manak                         By: /s/ Raymond M. Hakim, M.D., Ph.D.
   -----------------------------------         ---------------------------------
Name (print): Fred Manak                   Name (print): Raymond M. Hakim, M.D.,
              ------------------------                   Ph.D.
                                                         -----------------------
Title: Director Contracts and Pricinq     Title: Senior Executive Vice President
       -------------------------------           -------------------------------
Date:                                     Date:
     ---------------------------------           -------------------------------

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                                       11
<PAGE>
                                  Schedule 1.2

                             Authorized Wholesalers

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

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<PAGE>
                                  Schedule 1.4
                              Designated Affiliates



                                (to be inserted)


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                                       13
<PAGE>


                                  Schedule 1.10
                                 Managed Centers



                                (to be inserted)

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                                       14
<PAGE>
                                   Exhibit 3.1
                          Discount Terms and Conditions

*

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

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