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                                                                   EXHIBIT 10.21

                               GUARANTY AGREEMENT



     THIS GUARANTY AGREEMENT by SIMIONE CENTRAL, INC., a Georgia corporation
("Guarantor"), is made this 31st day of October, 1996, in favor of HCA, INC., a
Delaware corporation ("Acquiror").

                              W I T N E S S E T H:
                              - - - - - - - - - -

    WHEREAS, Guarantor as a subsidiary of SCHI (as hereinafter defined) is
presently an affiliate of Central Health Holding Company, Inc., a Delaware
corporation (the "Company"), and through certain subsidiaries provides skilled
intermittent home care services in the states of Georgia, Florida and Tennessee;

     WHEREAS, Acquiror and the Central Health Holding Company, Inc. Employee
Stock Ownership Plan (the "ESOP"), Gary M. Bremer and Rod D. Windley and certain
other stockholders of the Company (collectively, the "Stockholders") are parties
to that certain Stock Purchase Agreement dated as of September 19, 1996 (the
"Stock Purchase Agreement"), pursuant to which Acquiror shall purchase
substantially all of the capital stock of the Company;

        WHEREAS, Simione Central Holding Company, Inc. ("SCHI") is the parent
company of Guarantor, which provides consulting, information system and
management services to home health agencies;

     WHEREAS, the ESOP and certain stockholders of the Company are stockholders
of SCHI;

     WHEREAS, Acquiror has requested and Guarantor has agreed to provide home
health agency management and information services to certain hospital based home
health agencies that are owned and operated by affiliates of Acquiror; and

     WHEREAS, in order for Acquiror to consummate the transactions contemplated
by the Stock Purchase Agreement and in consideration of Acquiror causing its
affiliates to enter into home health agency management and information
management services contract with Guarantor, Guarantor desires to guaranty
certain obligations of the Stockholders set forth in the Stock Purchase
Agreement as set forth herein.

      NOW, THEREFORE, (i) in consideration of Acquiror causing its affiliates
to enter into home health agency management and information management services
contracts with Guarantor, (ii) at the special request of the stockholders of the
Company and of the Acquiror and (iii) for other good and valuable consideration,
the receipt and sufficiency of which is hereby forever acknowledged and
confessed, Guarantor and Acquiror hereby agree as follows:

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                                    ARTICLE 1

                                     GENERAL

     Section 1.01 Terms Defined Above. As used in this Guaranty Agreement, the
terms Acquiror, ESOP, Guarantor, SCHI, Stockholders and Stock Purchase Agreement
shall have the meanings indicated above.

     Section 1.02 Certain Definitions. As used in this Guaranty Agreement, the
following terms shall have the following meanings, unless the context otherwise
requires:

          "Guaranty Agreement" shall mean this Guaranty Agreement, as the same
     may from time to time be amended or supplemented.

          "Guaranteed Obligations" shall have the meaning indicated in Section
     2.01 hereof.

          "Minority Stockholders" shall mean all of the Stockholders other than
     the ESOP.

     Section 1.03 Definitions. All terms beginning with a capital letter which
are defined in the Stock Purchase Agreement shall have the same meanings herein
as therein unless clearly indicated to the contrary herein.

                                    ARTICLE 2

                                  THE GUARANTY

         Section 2.01 Payment Guaranteed. (a) Subject to the terms set forth
herein, Guarantor hereby absolutely, unconditionally and irrevocably guarantees
to Acquiror the full and faithful payment (i) by the ESOP, for any Loss (x)
incurred or suffered as a result of or arising under any one of the matters
described in Section 12.01 (c), (d), (f), (g) or (k)(i) of the Stock Purchase
Agreement or (y) which is not paid to Acquiror based on a claim by a person
other than any Acquiror Indemnified Person that the payment of such amount to
Acquiror for such Losses is a fiduciary breach, prohibited transaction or other
violation of law relating to the CHHC Plan (with such limitations or conditions
as provided by the Stock Purchase Agreement, including, without limitation,
those set forth in Sections 12.01, 12.02, 12.04 and 12.05), (ii) by the Minority
Stockholders for any Losses incurred or suffered as a result of or arising under
any of the matters described in Section 12.01(c), (d), (f), (g) or (k)(i) of the
Stock Purchase Agreement (with such limitations or conditions as provided by the
Stock Purchase Agreement, including, without limitation, those set forth in
Sections 12.01, 12.02, 12.04 and 12.05), and (iii) of the matters described in
Section 2.01(d) hereof (the "Guaranteed Obligations"). Subject to the terms and
conditions set forth herein and the Stock Purchase Agreement, if for any reason
or under any contingency the Stockholders do not pay Acquiror for the Guaranteed
Obligations, any Acquiror Indemnified Person shall have the option to require
Guarantor to assume all responsibility therefor in accordance with the procedure
set forth in Section 2.01(b) hereof, and Guarantor hereby agrees to assume all
responsibility therefor and, at its own costs and expense, to cause the
Guaranteed Obligations to be fully satisfied.



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     (b) Any Acquiror Indemnified Person may require Guarantor to pay such
person for a Guaranteed Obligation only as follows:

                  (i) If the Losses claimed by an Acquiror Indemnified Person
         are undisputed as evidenced by a written agreement signed by the duty
         authorized representatives of the Stockholders and the Escrow Agent
         does not release to Acquiror Escrowed Funds equal in amount to such
         Losses in accordance with the terms of the applicable escrow agreement
         or if such Escrowed Funds are less than the amount of such Losses and
         the Stockholders fail to pay Acquiror for such Losses in accordance
         with the terms of the Stock Purchase Agreement, then such Acquiror
         Indemnified Person may upon written notice to Guarantor require payment
         of same; provided, however, that for any ESOP payment obligation the
         Acquiror Indemnified Person must demand payment from the Minority
         Stockholders pursuant to the last paragraph of Section 12.01 of the
         Stock Purchase Agreement prior to requiring payment from Guarantor and
         the Minority Stockholders shall fail to pay such Losses in accordance
         with the Stock Purchase Agreement; or

                  (ii) If the Losses claimed by an Acquiror Indemnified Person
         are disputed, then to ascertain such Losses, Acquiror Indemnified
         Person must submit its claim for Losses to nonbinding arbitration as
         set forth in Section 13.09 of the Stock Purchase Agreement. If it is
         determined through such nonbinding arbitration that an Acquiror
         Indemnified Person has a Loss and the Escrow Agent does not release to
         Acquiror Escrowed Funds equal in amount to such Losses in accordance
         with the terms of the applicable escrow agreement or if such Escrowed
         Funds are less than the amount of such Losses and the Stockholders fail
         to pay Acquiror for such Losses in accordance with the terms of the
         Stock Purchase Agreement, then such Acquiror Indemnified Person may
         upon written notice to Guarantor require payment of same; provided,
         however, that for any ESOP payment obligation the Acquiror Indemnified
         Person must demand payment from the Minority Stockholders pursuant to
         the last paragraph of Section 12.01 of the Stock Purchase Agreement
         prior to requiring payment from Guarantor and the Minority Stockholders
         shall fail to pay same in accordance with the Stock Purchase Agreement;
         and

                (iii) In accordance with Section 2.01(b)(i) and 2.01(b)(ii), an
         Acquiror Indemnified Person shall actively pursue, in a commercially
         reasonable manner, the Stockholders to pay for such Losses prior to
         any demand for payment from the Guarantor.

         (c) Notwithstanding anything herein to the contrary, Guarantor's
maximum liability under this Guaranty Agreement shall be limited in the
aggregate to $20,000,000 for Guaranteed Obligations deemed to arise on or before
the first anniversary date of the Closing Date; $17,500,000 for Guaranteed
Obligations deemed to arise on or before the second anniversary date of the
Closing Date; $15,000,000 for Guaranteed Obligations deemed to arise on or
before the third anniversary date of the Closing Date; $15,000,000 for
Guaranteed Obligations deemed to arise on or before the fourth anniversary date
of the Closing Date, and $0 for Guaranteed Obligations arising thereafter.
Guaranteed Obligations deemed to arise in any year which are thereafter paid by
Guarantor to an Acquiror Indemnified Person shall be applied to each year for
purposes of determining the maximum


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liability in a given year. Notwithstanding anything herein to the contrary, in
no event shall Guarantor's maximum liability hereunder exceed $20,000,000 in the
aggregate.

         (d) If Guarantor pays an Acquiror Indemnified Person for a Guaranteed
Obligation and Guarantor or anyone acting by, through or under Guarantor
collects any sum of money from the ESOP, any successor thereto or the
beneficiaries of the ESOP (the "ESOP Parties"), which collection is based upon
Guarantor's payment of such Guaranteed Obligation to an Acquiror Indemnified
Person, then for purposes of determining Guarantor's liability hereunder the sum
of all such collections from the ESOP Parties relating to such Guaranteed
Obligations shall be added to the maximum liability of Guarantor under this
guaranty (but not in excess of the amounts set forth in Section 2.01(c) for the
period in which the Guaranteed Obligation was deemed to arise) for the limited
purpose of guaranteeing Guarantor's payment of the Guaranteed Obligations, if
any, that result from the collection by Guarantor of such sum of money from the
ESOP Parties, regardless of when such Guaranteed Obligation arises.

         (e) A Guaranteed Obligation shall be deemed to arise when the
Stockholders receive notice of an Asserted Claim from an Acquiror Indemnified
Person in accordance with Section 12.05 of the Stock Purchase Agreement;
provided, however, a claim under Section 2.01(d) is deemed to arise on the date
the Guaranteed Obligation to which such claim relates was deemed to arise.

         (f) As an interested party, Guarantor shall have the right to
participate in nonbinding arbitration between an Acquiror Indemnified Person and
the Stockholders to assert defenses and claims regarding the disputed Losses on
behalf of the Stockholders. Guarantor hereby agrees that any defenses or claims
it may have by or on behalf of itself or the Stockholders regarding the
validity, existence, nature, scope or amount of any claimed Losses shall only be
asserted at the time that the Stockholders are able to assert their defenses or
claims either through nonbinding arbitration as required by Section 13.09 of the
Stock Purchase Agreement or before a court of competent jurisdiction if the
determination of such nonbinding arbitration is not brought before such court.

         Section 2.02 Obligations Absolute and Unconditional. (a) Subject to the
terms, conditions and limitations set forth herein, the obligations of Guarantor
under this Guaranty Agreement shall be absolute, unconditional and irrevocable
and shall remain in full force and effect until there shall be no duties,
obligations, covenants, agreements or liabilities of the Stockholders or
Guarantor in respect of the Guaranteed Obligations as set forth in Section 2.01
above, and until such collection by an Acquiror Indemnified Person, such
obligations shall not be affected, modified or impaired upon the happening from
time to time of any act or failure to act by any Acquiror Indemnified Person,
whether or not with notice to or the consent of Guarantor, with respect only to
the following:


               (i) the failure to give notice to Guarantor of the occurrence of
          a default under the terms and provisions of this Guaranty Agreement or
          the Stock Purchase Agreement, as applicable;

               (ii) the waiver of the payment, performance or observa nce by the
          Stockholders, of any of the obligations, covenants, or agreements of
          any Acquiror Indemnified Person contained in the Stock Purchase
          Agreement;



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               (iii) the extension of the time for performance of any
          obligations, covenants or agreements under or arising out of the Stock
          Purchase Agreement or under or arising out of this Guaranty Agreement,
          or the extension or the renewal of any thereof,

               (iv) the modification or amendment (whether material or
          otherwise) of any obligation, covenant or agreement set forth in the
          Stock Purchase Agreement;

               (v) the taking or the omission of any actions by the Stockholders
          referred to in the Stock Purchase Agreement; or

               (vi) any failure, omission, delay or lack on the part of the
          Stockholders to enforce, assert or exercise any right, power or remedy
          conferred on the Stockholders in the Stock Purchase Agreement at law
          or in equity, or any other act or acts on the part of the
          Stockholders.

         (b) This Guaranty Agreement is not conditioned or contingent upon the
enforceability of the Stock Purchase Agreement or other instruments relating to
the creation of performance of the Guaranteed Obligations as to or against the
Stockholders, except to the extent that any obligation of the Acquiror is
determined to be invalid or unenforceable for any reason and such invalidity or
unenforceability gives rise to the claim which is the subject of the Guaranteed
Obligations.

         (c) Subject to the terms set forth herein (including without limitation
the right of offset set forth herein) this Guaranty Agreement and the
obligations of Guarantor hereunder shall be valid and enforceable and, subject
to the terms set forth herein, shall not be subject to any reduction,
limitation, impairment, discharge or termination for any reason other than
prompt and complete payment and performance of the Guaranteed Obligations.

         (d) In the event that all or any portion of the Guaranteed Obligations
are paid by the Stockholders, the obligation of Guarantor under this Guaranty
Agreement shall continue and remain in full force and effect to be reinstated as
the case may be, in the event that all or any part of any such payment(s) are
rescinded or recovered directly or indirectly from an Acquiror Indemnified
Person as a preference, fraudulent transfer or otherwise, and any such payments
that are so rescinded or recovered shall constitute Guaranteed Obligations for
all purposes, as of the date of such payment of the Guaranteed Obligations.

         (e) Guarantor hereby waives for the benefit of any Acquiror Indemnified
Person any defense of the Stockholders arising by reason of incapacity, lack of
authority, lack of consideration, failure of consideration, illegality, duress,
undue influence or fiduciary breaches, prohibited transactions or other
violations of law relating to the CHHC Plan with respect to the Stock Purchase
Agreement or any agreement or instrument relating to the Stock Purchase
Agreement.

         (f) Guarantor hereby waives for the benefit of any Acquiror Indemnified
Person any defense arising by reason of incapacity, lack of authority, lack or
failure of consideration, illegality, duress, undue influence or any disability
or defense of Guarantor based on or arising out of the lack of validity or the
unenforceability of this Guaranty Agreement.

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     (g) Guarantor hereby waives for the benefit of any Acquiror Indemnified
Person any defense based upon any statute or rule of law that provides that the
obligation of a surety must be neither larger in amount nor in other respects
more burdensome than that of principal.

                                    ARTICLE 3

                         REPRESENTATIONS AND WARRANTIES

     Guarantor hereby represents and warrants as of the date hereof that:

     Section 3.01. Organization and Qualification Subsidiaries. Guarantor is a
corporation, and each of Guarantor's other subsidiaries is a corporation duly
organized, validly existing and in good standing under the laws of its
jurisdiction of incorporation and has all requisite corporate power and
authority to own, lease and operate its properties and to carry on its business
as it is now being conducted and is duly qualified and in good standing to do
business in each jurisdiction in which the nature of the business conducted by
it or the ownership or leasing of its properties makes such qualification
necessary.

     Section 3.02 Certificate of Incorporation and Bylaws. Guarantor has
heretofore furnished or made available to Acquiror complete and correct copies
of the Articles of Incorporation and Bylaws, in each case as amended or restated
to the date hereof, of Guarantor.

     Section 3.03 Authority. Guarantor has all requisite corporate power and
authority to execute and deliver this Agreement, to perform its obligations
hereunder and to consummate the transactions contemplated hereby.  The execution
and delivery of this Agreement by Guarantor and the consummation by Guarantor of
the transactions contemplated hereby have been duly authorized by all necessary
corporate action and all other corporate proceedings on the part of Guarantor
that are necessary to authorize this Agreement or to consummate the transactions
contemplated hereby. This Agreement has been duly executed and delivered by
Guarantor and constitutes the legal, valid and binding obligation of Guarantor.

     Section 3.04 No Conflict. The execution and delivery of this Guaranty
Agreement by Guarantor does not, and the performance by Guarantor of its
obligations hereunder will not (i) conflict with or violate the Articles of
Incorporation or Bylaws, in each case and as amended and restated, of Guarantor,
(ii) conflict with or violate any federal, state, foreign or local law, statute,
ordinance, rule or regulation in effect as of the date hereof (collectively,
"Laws') applicable to Guarantor or any judgment, order or decree applicable to
Guarantor or by which any of its properties is bound or subject or (iii) result
in any breach of or constitute a default (or an event that with notice or lapse
of time or both would become a default) under, or give rise to others any right
of termination, amendment, acceleration or cancellation of, or require payment
under, or result in the creation of a lien or encumbrance on any of the
properties or assets of Guarantor pursuant to, any note, bond, mortgage,
indenture, contract, agreement, lease, license, permit, franchise or other
instrument or obligation to which the Company is a party or by which the Company
or its properties is bound or subject.





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                                    ARTICLE 4

                              PAYMENT OF OBLIGATION

         Section 4.01 Right of Offset/Recoupment. (a) Guarantor hereby expressly
authorizes and grants Acquiror and any affiliate of Acquiror that receives
management or information services from Guarantor the absolute right to offset
and recoup from any obligation of such persons to Guarantor (on a pro rata basis
determined in accordance with the annual fees payable under such management and
information services agreements) any Guaranteed Obligations that are required to
be paid by Guarantor hereunder. If the Guaranteed Obligations to be paid by
Guarantor exceed $500,000, then Acquiror and Guarantor hereby agree to negotiate
in good faith for a payment plan for Guarantor whereby such persons shall apply
the right of offset and recoupment granted hereby over an agreed upon period of
time. It is hereby agreed that in no event shall such payment plan extend beyond
the later to occur of (i) the fifth anniversary date of this Guaranty Agreement
or (ii) the second anniversary date of the accrual of such Guaranteed
Obligation.

         (b) Acquiror hereby expressly authorizes and grants Guarantor the
absolute right to offset and recoup against the payment of any Guaranteed
Obligations to be paid by Guarantor hereunder, the amount of any undisputed
obligation of the affiliates of Acquiror under the home health agency management
and information management services contracts between such affiliates and
Guarantor.

         Section 4.02 Security Interest. Guarantor hereby agrees that as of each
date that a Guaranteed Obligation is required to be paid by Guarantor hereunder,
Guarantor pledges, assigns and grants to Acquiror a security interest equal to
the entire amount of such Guaranteed Obligation in all of Guarantor's accounts
receivable, subject only to a security interest in the accounts receivable of
Guarantor granted by Guarantor prior to the date hereof to a third party, to
secure the prompt payment and performance of the Guaranteed Obligations by
Guarantor as set forth herein. Guarantor hereby agrees to execute such security
instruments as requested by Acquiror to secure these obligations.

                                    ARTICLE 5

                                  MISCELLANEOUS

         Section 5.01 Successors and Assigns. (a) This Guaranty Agreement is a
continuing obligation of Guarantor and is not assignable without the express
written consent of Acquiror. 'Ibis Guaranty Agreement shall (i) be binding upon
Guarantor and its successors and assigns, and (ii) inure to the benefit of and
be enforceable by any Acquiror Indemnified Person. This Guaranty Agreement is
intended solely for the benefit of each Acquiror Indemnified Person and it is
not the intention of Guarantor to confer third party beneficiary rights upon any
other person.

         (b) Guarantor hereby agrees that it shall not assign any home health
agency management agreement or information management services agreement entered
into by and between Guarantor and any affiliate of Acquiror without the express
written consent of Acquiror, which consent shall not be unreasonably withheld or
delayed. It is hereby agreed that Acquiror shall make a determination of whether
Guarantor shall be able to satisfy its obligations hereunder in determining
whether to grant such consent and that Acquiror may require such proposed
assignee to assume certain obligations hereunder as a condition to such consent.

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     Section 5.02 Preservation of Rights. Notwithstanding anything set forth
herein, any Acquiror Indemnified Person may provide notice to Guarantor or
institute any legal action it deems necessary in order to preserve and not to
jeopardize its rights against Guarantor hereunder.

     Section 5.03 Notices. All notices, requests and other communications
hereunder shall be in writing and shall be given to the party to whom sent,
addressed to it as follows:

If directed to Acquiror:

                             HCA, Inc.
                             One Park Plaza
                             Nashville, Tennessee 37203
                             Attn:Vice President, Development
                             Fax: (615) 320-2558

         with a copy to:

                             Columbia/HCA Healthcare Corporation
                             One Park Plaza
                             Nashville, Tennessee 37203
                             Attn:General Counsel
                             Fax: (615) 320-2598

If directed to Guarantor:

                             Simione Central, Inc.
                             6650 Powers Ferry Road
                             Suite 200
                             Atlanta, Georgia 33039
                             Attn:President
                             Fax: (770) 644-6559

with a copy to:

                             Simione Central, Inc.
                             6650 Powers Ferry Road
                             Suite 200
                             Atlanta, Georgia 33039
                             Attn:General Counsel
                             Fax: (770) 644-6559

Acquiror and Guarantor may designate a different address to which such notices
should be sent by giving the other written notice thereof. Each such notice,
request or communication shall be effective when received by telefax or other
electronic means or overnight courier, or three (3) days after being deposited
in the United States Mail, with postage prepaid thereon, registered or certified
mail, return receipt requested, addressed as aforesaid or, if given by any other
means, when delivered at the address of the party to whom such notice is being
delivered.

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     Section 5.04 Amendments. This Guaranty Agreement may be amended only upon
the written consent of Acquiror and Guarantor. No course of dealing between
Guarantor nor any delay in exercising any rights hereunder, shall operate as a
waiver of any rights of any Acquiror Indemnified Person hereunder.

     Section 5.05 Severability. Any provision of this Guaranty Agreement which
is prohibited, unenforceable or not authorized shall be fully severable and this
Guaranty Agreement shall be construed and enforced as if such prohibited,
unenforceable, or unauthorized provision had never comprised a part
hereof

     Section 5.06 Governing Law. This Guaranty Agreement is intended to be
performed in the state of Georgia, and shall be construed and enforced in
accordance with, and the rights of the parties shall be governed by, the laws of
the state of Georgia, excluding any conflicts of law, rule or principal that
might refer the governance or the construction of this Guaranty Agreement to the
laws of another jurisdiction.

     Section 5.07 Entire Agreement; Multiple Counterparts. This Guaranty
Agreement constitutes the entire agreement, and supersedes all prior agreements
and understandings, both written and oral, among the parties with respect to the
subject matter hereof and may be executed simultaneously in several
counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.

     IN WITNESS WHEREOF, Guarantor has duly executed and delivered this Guaranty
Agreement, or caused same to be duly executed and delivered as of the date first
set above.

GUARANTOR:                            SIMIONE CENTRAL, INC.



                                      By: /s/ Gary M. Bremer
                                         ----------------------------------
                                      Gary M. Bremer
                                      Chief Executive Officer



ACQUIROR:                             HCA, INC.



                                       By: /s/ C. Michael Ford
                                          ----------------------------------
                                       C. Michael Ford
                                       Vice President



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