Document:

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                                                                   EXHIBIT 10.28

CONTRACT WITH APPROVED ENTITY PURSUANT TO SECTIONS 1860D-1 THROUGH 1860D-42 OF
THE SOCIAL SECURITY ACT FOR THE OPERATION OF A VOLUNTARY MEDICARE PRESCRIPTION
DRUG PLAN

                                     BETWEEN

   CENTERS FOR MEDICARE & MEDICAID SERVICES (HEREINAFTER REFERRED TO AS "CMS")

                                       AND

              HEALTHSPRING, INC. D/B/A/ HEALTHSPRING OF MISSISSIPPI
                                     (S5815)

(A PRESCRIPTION DRUG PLAN SPONSOR, HEREINAFTER REFERRED TO AS THE "PDP SPONSOR")

CMS and the PDP Sponsor, an entity that has been determined eligible to operate
a Voluntary Medicare Prescription Drug Plan by the Administrator of CMS under
423 CFR Section 423.503, agree to the following for the purposes of sections
1860D-l through 1860D-42 (with the exception of sections 1860D-22(a) and
1860D-31) of the Social Security Act (hereinafter referred to as "the Act").

                                   ARTICLE I.
                  MEDICARE VOLUNTARY PRESCRIPTION DRUG BENEFIT

A.   PDP Sponsor agrees to operate one or more Medicare Voluntary Prescription
     Drug Plans (hereinafter referred to as a "PDP"), as described in its
     application and related materials, including but not limited to all the
     attestations contained therein and all supplemental guidance, for Medicare
     approval and in compliance with the provisions of this contract, which
     incorporates in its entirety the Solicitation For Applications from
     Prescription Drug Plans released on January 21, 2005 (as revised on March
     9, 2005) (hereinafter collectively referred to as "the contract"). The PDP
     Sponsor also agrees to operate in accordance with the regulations at 42 CFR
     Section 423.1 through 42 CFR Section 423.910 (with the exception of
     Subparts Q, R and S), sections 1860D-1 through 1860D-42 (with the exception
     of sections 1860D-22(a) and 1860D-31) of the Social Security Act, and the
     solicitation, as well as all other applicable Federal statutes, regulations
     and policies. This contract is deemed to incorporate any changes that are
     required by statute to be implemented during the term of this contract and
     any regulations or policies implementing or interpreting such statutory
     provisions.

B.   CMS agrees to perform its obligations to the PDP Sponsor consistent with
     the regulations at 42 CFR Section 423.1 through 42 CFR Section 423.910
     (with the exception of Subparts Q, R and S), sections 1860D-1 through
     l860D-42 of the Social Security Act (with the exception of sections
     1860D-22(a) and 1860D-31) and the solicitation, as well as all other
     applicable

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     Federal statutes, regulations and policies.

C.   CMS agrees that it will not implement, other than at the beginning of a
     calendar year, regulations under 42 CFR Part 423 that impose new,
     significant regulatory requirements on the PDP Sponsor. This provision does
     not apply to new requirements mandated by statute.

D.   This contract is in no way intended to supersede or modify 42 CFR, Part
     423. Failure to reference a regulatory requirement in this contract does
     not affect the applicability of such requirements to the PDP Sponsor and
     CMS.

                                  ARTICLE II.
                  FUNCTIONS TO BE PERFORMED BY THE PDP SPONSOR

A.   ENROLLMENT

     1.   PDP Sponsor agrees to accept new enrollments, make enrollments
          effective, process voluntary disenrollments and limit involuntary
          disenrollments, as described in 42 CFR, Part 423, Subpart B.

     2.   PDP Sponsor agrees to comply with the prohibition in 42 CFR 423.104(b)
          on discrimination in beneficiary enrollment.

B.   PRESCRIPTION DRUG BENEFIT

     1.   PDP Sponsor agrees to provide the basic prescription drug coverage as
          defined under 42 CFR Section 423.100 and, to the extent applicable,
          supplemental benefits as defined in 42 CFR Section 423.100 and in
          accordance with Subpart C of 42 CFR Part 423. PDP Sponsor also agrees
          to provide Part D benefits as described in the PDP Sponsor's bid(s)
          approved each year by CMS (as referenced in Attachment A, to be
          replaced each year upon renewal of the contract to reflect the
          Sponsor's approved bid for the succeeding contract year).

     2.   PDP Sponsor agrees to calculate and collect beneficiary premiums in
          accordance with 42 CFR Sections 423.286 and 423.293.

C.   DISSEMINATION OF PLAN INFORMATION

     1.   PDP Sponsor agrees to provide the information required in 42 CFR
          Section 423.48.

     2.   PDP Sponsor agrees to disclose information to beneficiaries in the
          manner and the form specified by CMS under 42 CFR Sections 423.l28,
          423.50 and in the "Marketing Materials Guidelines for Medicare
          Advantage-Prescription Drug Plans (MA-PDs) and Prescription Drug Plans
          (PDPs)," and to comply with requirements in 42 CFR Section 423.50
          requiring certain approvals of marketing materials prior to
          distribution.

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     3.   PDP Sponsor certifies that all materials it submits to CMS under the
          File and Use Certification authority described in the Marketing
          Materials Guidelines are accurate, truthful, not misleading and
          consistent with CMS marketing guidelines.

D.   QUALITY ASSURANCE/UTILIZATION MANAGEMENT

     PDP Sponsor agrees to operate quality assurance, drug utilization
     management and medication therapy management programs, and to support
     electronic prescribing in accordance with Subpart D of 42 CFR Part 423.

E.   APPEALS AND GRIEVANCES

     PDP Sponsor agrees to comply with all requirements in Subpart M of 42 CFR
     Part 423 governing coverage determinations, grievances and appeals, and
     formulary exceptions.

F.   PAYMENT TO PDP SPONSOR

     1.   PDP Sponsor and CMS agree that payment under this contract will be
          governed by the rules in Subpart G of 42 CFR Part 423.

     2.   If the PDP Sponsor is participating in the Part D Reinsurance Payment
          Demonstration described in 70 FR 9360 (Feb. 25, 2005), it affirms that
          it will not seek payment under the demonstration for services provided
          to employer group enrollees.

     3.   PDP Sponsor agrees that it is bound by all applicable federal laws and
          regulations, guidance and authorities pertaining to claims and debt
          collections. In the event that the government determines that the PDP
          Sponsor has been overpaid, the PDP Sponsor agrees to return those
          overpaid monies back to the federal government.

G.   BID SUBMISSION AND REVIEW

     If the PDP Sponsor intends to participate in the Part D program for the
     next program year, PDP Sponsor agrees to submit the next year's bid,
     including all required information on premiums, benefits and cost-sharing,
     by the applicable due date, as provided in Subpart F of 42 CFR Part 423 so
     that CMS and the Part D plan sponsor may conduct negotiations regarding the
     terms and conditions of the proposed bid and benefit plan renewal.

H.   STATE LAW AND LICENSURE REQUIREMENTS

     1.   PDP Sponsor agrees to comply with State law to the extent that it is
          not preempted by Federal law as described in Subpart I of 42 CFR Part
          423.

     2.   PDP Sponsor agrees that where it is operating in a State using a
          waiver granted pursuant to 42 CFR Section 423.410, such waiver shall
          be valid for three consecutive

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          program years. PDP Sponsor agrees that expiration of the licensure
          waiver (and the failure to obtain a license from the relevant State)
          may be the basis for CMS deleting from the PDP Sponsor's service area
          those PDP Regions affected by the waiver expiration. CMS may terminate
          or non-renew the PDP Sponsor's contract where the expiration of the
          waiver results in the PDP Sponsor not being qualified to offer a PDP
          plan in any PP Region.

     3.   PDP Sponsor agrees that where it is operating in a State using a
          waiver granted pursuant to 42 CFR Section 423.415, such waiver shall
          be valid for the period that the Secretary of the Department of Health
          and Human Services determines is appropriate for timely processing of
          the PDP Sponsor's license application by the State, but in no case no
          more than one year only, beginning on January 1 of the contract year
          for which CMS granted the waiver.

I.   COORDINATION WITH OTHER PRESCRIPTION DRUG COVERAGE

     1.   PDP Sponsor agrees to comply with the coordination requirements with
          State Pharmacy Assistance Programs (SPAPs) and plans that provide
          other prescription drug coverage as described in Subpart J of 42 CFR
          Part 423.

     2.   PDP Sponsor agrees to comply with Medicare Secondary Payer procedures
          as stated in 42 CFR Section 423.462.

J.   SERVICE AREA AND PHARMACY ACCESS

     1.   The PDP Sponsor agrees to provide Part D benefits in the service area
          for which it has been approved by CMS utilizing a pharmacy network and
          formulary approved by CMS that meet the requirements of 42 CFR Section
          423.120.

     2.   The PDP Sponsor agrees to provide Part D benefits through
          out-of-network pharmacies according to 42 CFR Section 423.124.

     3.   PDP Sponsor agrees to provide benefits by means of point of service
          systems to adjudicate prescription drug claims in a timely and
          efficient manner in compliance with CMS standards, except when
          necessary to provide access in underserved areas, I/T/U pharmacies (as
          defined in 42 CFR Section 423.100) and long-term care pharmacies (as
          defined in 42 CFR Section 423.100).

     4.   PDP Sponsor agrees to contract with any pharmacy that meets the PDP
          Sponsor's reasonable and relevant standard terms and conditions.

K.   COMPLIANCE PLAN/PROGRAM INTEGRITY

     1.   PDP Sponsor agrees that it will develop and implement a compliance
          plan that applies to its Part D-related operations, consistent with 42
          CFR Section 423.504(b)(4)(vi).

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     2.   The PDP sponsor agrees to provide notice based on best knowledge,
          information and belief to CMS of any integrity items related to
          payments from governmental entities, both federal and state, for
          healthcare or prescription drug services that would have been reported
          as part of 3.1.4 of the PDP application. These items include any
          investigations, legal actions or matters subject to arbitration
          brought involving the sponsor (or sponsor's firm if applicable) and
          its subcontractors (excluding contracted network providers), including
          any key management or executive staff, or any major shareholders (5%
          or more), by a government agency (state or federal) on matters
          relating to payments from governmental entities, both federal and
          state, for healthcare and/or prescription drug services. In providing
          the notice, the sponsor shall keep the government informed of when the
          integrity item is initiated and when it is closed. Notice should be
          provided of the details concerning any resolution and monetary
          payments as well as any settlement agreements or corporate integrity
          agreements.

     3.   The PDP Sponsor agrees to provide notice based on best knowledge,
          information and belief to CMS in the event the Sponsor or any of its
          subcontractors is criminally convicted or has a civil judgment entered
          against it for fraudulent activities or is sanctioned under any
          Federal program involving the provision of health care or prescription
          drug services.

L.   LOW-INCOME SUBSIDY

     PDP Sponsor agrees that it will participate in the administration of
     subsidies for low-income individuals according to Subpart P of 42 CFR Part
     423.

M.   COMMUNICATION WITH CMS

     PDP Sponsor agrees that it shall maintain the capacity to communicate with
     CMS electronically in accordance with CMS requirements.

N.   BENEFICIARY FINANCIAL PROTECTIONS

     The PDP Sponsor agrees to afford its enrollees protection from liability
     for payment of fees that are the obligation of the PDP Sponsor in
     accordance with 42 CFR Section 423.505(g).

O.   RELATIONSHIP WITH RELATED ENTITIES, CONTRACTORS AND SUBCONTRACTORS

     1.   The PDP Sponsor agrees it maintains ultimate responsibility for
          adhering to and otherwise fully complying with all terms and
          conditions of this contract with CMS.

     2.   The PDP Sponsor shall ensure that any contracts or agreements with
          subcontractors or agents performing functions on the PDP Sponsor's
          behalf

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          related to the operation of the Part D benefit are in compliance with
          42 CFR Section 423.505(i).

     3.   The PDP Sponsor agrees to act in accordance with 45 CFR Part 76 and
          agrees that it will not contract with or employ entities or
          individuals that are excluded by the Department of Health and Human
          Services, Office of the Inspector General or included on the Excluded
          Parties List System maintained by the General Services Administration.

P.   CERTIFICATION OF DATA THAT DETERMINE PAYMENT

     PDP Sponsor must provide certifications in accordance with 42 CFR Section
     423.505(k).

Q.   ENROLLMENT RELATED COSTS

     PDP Sponsor agrees to payment of fees established by CMS for cost sharing
     of enrollment related costs in accordance with 42 CFR Section 423.6.

                                  ARTICLE III.
                   RECORD RETENTION AND REPORTING REQUIREMENTS

A.   RECORD MAINTENANCE AND ACCESS

     PDP Sponsor agrees to maintain records and provide access in accordance
     with 42 CFR Sections 423.504(d) and 423.505(d) and (e).

B.   GENERAL REPORTING REQUIREMENTS

     The PDP Sponsor agrees to submit information to CMS according to 42 CFR
     Sections 423.505(f), 423.514 and the "Final Medicare Part D Reporting
     Requirements," a document issued by CMS and subject to modification each
     program year.

C.   LICENSURE-RELATED REPORTING REQUIREMENTS

     1.   If the PDP Sponsor is operating under a CMS-granted licensure waiver
          in any State, the PDP Sponsor agrees to notify CMS in writing of the
          State's disposition of the Sponsor's license application within ten
          (10) business days of the date that it receives notice of the State's
          action.

     2.   For those States where the PDP Sponsor is operating under a
          risk-bearing license, the Sponsor agrees to provide written notice to
          CMS of the State's non-renewal of the Sponsor's license within ten
          days of receiving notice of the State's action.

     3.   In the event that a State regulator imposes a sanction against the PDP
          Sponsor or requires the implementation of a corrective action plan,
          the Sponsor agrees to provide written notice to CMS of such sanction
          or corrective action requirement

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          (including basis for the sanction and/or timeline for corrective
          action) within ten days of receiving notice of the State's action.

     4.   In the event that there is a change in the status of the PDP Sponsor's
          risk-bearing license in any State (e.g., suspension, revocation), the
          Sponsor agrees to provide written notice to CMS of the change in
          status (including basis for the change in status and effective date)
          within ten days of receiving notice of the State's action.

     5.   If the PDP Sponsor is operating a Part D benefit under a CMS-granted
          waiver in every State in its service area, and the Sponsor is
          terminating or reducing the amount of an existing letter of credit
          obtained for the purposes of funding projected losses, the Sponsor
          shall provide written notice to CMS of such action thirty (30) days
          prior to its effective date. The PDP Sponsor agrees that it must
          obtain CMS approval prior to terminating or reducing the amount of a
          letter of credit obtained for the purposes of funding projected losses
          under Appendix X of the PDP Solicitation.

D.   CMS LICENSE FOR USE OF PLAN FORMULARY

     PDP Sponsor agrees to submit to CMS each plan's formulary information,
     including any changes to its formularies, and hereby grants to the
     Government [and any person or entity who might receive the formulary from
     the Government,] a non-exclusive license to use all or any portion of the
     formulary for any purpose related to the administration of the Part D
     program, including without limitation publicly distributing, displaying,
     publishing or reconfiguration of the information in any medium, including
     www.medicare.gov, and by any electronic, print or other means of
     distribution.

                                  ARTICLE IV.
                                HIPAA PROVISIONS

                       HIPAA TRANSACTIONS/PRIVACY/SECURITY

A.   PDP Sponsor agrees to comply with the confidentiality and enrollee record
     accuracy requirements specified in 42 CFR Section 423.136.

B.   PDP Sponsor agrees to enter into a business associate agreement with the
     entity with which CMS has contracted to track Medicare beneficiaries' true
     out-of-pocket costs.

                                   ARTICLE V.
                   REQUIREMENTS OF OTHER LAWS AND REGULATIONS

     The PDP Sponsor agrees to comply with (a) applicable Federal laws and
regulations designed to prevent fraud, waste and abuse, including, but not
limited to applicable provisions of Federal criminal law, the False Claims Act
(31 U.S.C. Sections 3729 et seq.), and the anti-kickback provision of section
1128B of the Act; (b) applicable HIPAA Administrative Simplification

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Security and Privacy rules at 45 CFR parts 160, 162 and 164; and (c) all other
applicable Federal statutes and regulations.

                                  ARTICLE VI.
                            CONTRACT TERM AND RENEWAL

A.   TERM OF CONTRACT

     This contract is effective from the date of CMS' authorized
     representative's signature through December 31, 2006. This contract shall
     be renewable for successive one-year periods thereafter according to 42 CFR
     Section 423.506. PDP Sponsor shall not conduct Part D-related marketing
     activities prior to October 1, 2005 and shall not process enrollment
     applications prior to November 15, 2005. PDP Sponsor shall begin delivering
     prescription drug benefit services on January 1, 2006.

B.   QUALIFICATION TO RENEW A CONTRACT

     1.   In accordance with 42 CFR Section 423.507, the PDP Sponsor will be
          determined qualified to renew its contract annually only if:

          (a)  CMS informs the PDP Sponsor that it is qualified to renew its
               contract; and

          (b)  The PDP Sponsor has not provided CMS with a notice of intention
               not to renew in accordance with Article VII of this contract.

     2.   Although PDP Sponsor may be determined qualified to renew its contract
          under this Article, if the PDP Sponsor and CMS cannot reach agreement
          on the bid under Subpart F of 42 CFR Part 423, no renewal takes place
          and the failure to reach agreement is not subject to the appeals
          provisions in Subpart N of 42 CFR Part 423.

                                  ARTICLE VII.
                             NONRENEWAL OF CONTRACT

A.   NONRENEWAL BY THE PDP SPONSOR

     1.   The PDP Sponsor may elect not to renew its contract with CMS,
          effective at the end of the term of the contract for any reason as
          long as PDP Sponsor provides proper notice of the decision according
          to the required timeframes.

     2.   If the PDP Sponsor does not intend to renew its contract, it must
          notify:

          (a)  CMS in writing by the first Monday of June in the year in which
               the current contract period ends;

          (b)  Each Medicare enrollee, at least ninety (90) days before the date
               on which the nonrenewal is effective. This notice must include a
               written description

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               of alternatives available for obtaining qualified prescription
               drug coverage within the PDP region, including Medicare
               Advantage-Prescription Drug plans, Medicare cost plans offering a
               Part D plan and other PDPs and must receive CMS approval prior to
               issuance; and

          (c)  The general public, at least ninety (90) days before the end of
               the current calendar year, by publishing a notice in one or more
               newspapers of general circulation in each community or county
               located in the Part D plan sponsor's service area.

     3.   If the PDP Sponsor does not renew a contract CMS cannot enter into a
          contract with the organization for two (2) years unless there are
          special circumstances that warrant special consideration, as
          determined by CMS.

     4.   If the PDP Sponsor does not renew a contract, it must ensure the
          timely transfer of any data or files in accordance with CMS
          instructions.

B.   NONRENEWAL BY CMS

     1.   CMS may determine that the PDP Sponsor is not qualified to renew its
          contract for any of the following reasons:

          (a)  The reasons listed in 42 CFR Section 423.509(a) that also permit
               CMS to terminate the contract.

          (b)  The PDP Sponsor has committed any of the acts in 42 CFR Section
               423.752 that support the imposition of intermediate sanctions or
               civil money penalties under 42 CFR Section 423.750.

     2.   CMS will provide notice of its decision whether the PDP Sponsor is
          qualified to renew its contract as follows:

               (i)  To the PDP Sponsor by May 1 of the current contract year.

               (ii) If CMS decides that the PDP Sponsor is not qualified to
                    renew its contract, to the PDP Sponsor's Medicare enrollees
                    by mail at least ninety (90) days before the end of the
                    current calendar year.

              (iii) If CMS determines that the PDP Sponsor is not qualified to
                    renew its contract, to the general public at least ninety
                    (90) days before the end of the current calendar year, by
                    publishing a notice in one (1) or more newspapers of general
                    circulation in each community or county located in the PDP
                    Sponsor's service area.

               (iv) CMS will provide the notice described in (B)(2)(ii) and
                    (iii) of this Article where a non-renewal results because
                    CMS and the PDP Sponsor are unable to reach agreement on the
                    bid under 42 CFR Part 423, Subpart F.

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     3.   CMS shall give the PDP Sponsor written notice of its right to appeal
          the decision that the sponsor is not qualified renew its contract in
          accordance with 42 CFR Section 423.642(b).

                                 ARTICLE VIII.
                     MODIFICATION OR TERMINATION OF CONTRACT

A.   CONTRACT MODIFICATION OR TERMINATION BY MUTUAL CONSENT

     1.   This contract may be modified or terminated at any time by written
          mutual consent of the parties.

     2.   If this contract is terminated by mutual consent, the PDP Sponsor must
          provide notice to its Medicare enrollees and the general public in
          accordance with CMS's instructions.

     3.   If the contract is modified by mutual consent, the PDP Sponsor must
          notify its Medicare enrollees of any changes that CMS determines are
          appropriate for notification according to the process and timeframes
          specified by CMS.

     4.   If a contract is terminated under section A of this Article, the PDP
          Sponsor must ensure the timely transfer of any data or files.

B.   TERMINATION OF CONTRACT BY CMS

     CMS may terminate the contract in accordance with 42 CFR Section 423.509.

C.   TERMINATION OF CONTRACT BY THE PDP SPONSOR

     The PDP Sponsor may terminate the contract only in accordance with 42 CFR
     Section 423.510.

                                  ARTICLE IX.
                             INTERMEDIATE SANCTIONS

     Consistent with Subpart O of 42 CFR Part 423, the PDP Sponsor shall be
subject to sanctions and civil money penalties.

                                   ARTICLE X.
                                  SEVERABILITY

     Severability of the contract shall be in accordance with 42 CFR 423.504(e).

                                   ARTICLE XI.
                                  MISCELLANEOUS

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A.   DEFINITIONS

     Terms not otherwise defined in this contract shall have the meaning given
     to such terms in 42 CFR Part 423.

B.   ALTERATION TO ORIGINAL CONTRACT TERMS

     The PDP Sponsor agrees that it has not altered in any way the terms of the
     PDP contract presented for signature by CMS. PDP Sponsor agrees that any
     alterations to the original text the PDP Sponsor may make to this contract
     shall not be binding on the parties.

C.   ADDITIONAL CONTRACT TERMS

     The PDP Sponsor agrees to include in this contract other terms and
     conditions in accordance with 42 CFR Section 423.505(j).

D.   CMS APPROVAL TO BEGIN MARKETING AND ENROLLMENT ACTIVITIES

     PDP Sponsor agrees that it must complete CMS operational requirements prior
     to receiving CMS approval to begin Part D marketing and enrollment
     activities. Such activities include, but are not limited to, establishing
     and successfully testing connectivity with CMS systems to process
     enrollment applications (or contracting with an entity qualified to perform
     such functions on PDP Sponsor's behalf) and successfully demonstrating
     capability to submit accurate and timely price comparison data. To
     establish and successfully test connectivity, the PDP Sponsor must, 1)
     establish and test physical connectivity to the CMS data center, 2) acquire
     user identifications and passwords, 3) receive, store and maintain data
     necessary to perform enrollments and send and receive transactions to and
     from CMS and 4) check and receive transaction status information.

     IN WITNESS WHEREOF, the parties hereby execute this contract.

FOR THE PDP SPONSOR:

JEFF ROTHENBERGER                            SR. VP & CORPORATE COO
--------------------------------------------------------------------------------
Printed Name                                 Title

/s/ Jeff Rothenberger                        9/7/05
--------------------------------------------------------------------------------
Signature                                    Date

HEALTHSPRING, INC. D/B/A HEALTHSPRING OF MISSISSIPPI
----------------------------------------------------
Organization

                                       11
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44 VANTAGE WAY, SUITE 300, NASHVILLE, TN  37228
-------------------------------------------------
Address

FOR THE CENTERS FOR MEDICARE & MEDICAID SERVICES:

/s/ Robert Donnelly                                 9/29/05
------------------------------------------------------------------------------
Robert Donnelly                                     Date
Director Medicare Drug Benefit Group
Center for Beneficiary Choices

                                       12

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                                  ATTACHMENT A

                      PART D BENEFIT PLAN(S) -- DESCRIPTION

                                       13

<PAGE>

          Prescription Drug Plan Attestation of Benefit Plan and Price

                               HEALTHSPRING, INC.

                                      S5815

                                Date: 09/06/2005

I attest that the following plan numbers as established in the final Plan
Benefit Package (PBP) will be operated by the above-stated organization and made
available to eligible Medicare beneficiaries in the approved service area during
program year 2006.

<Table>
<Caption>
------------------------------------------------------------------------------------------------------------------------------------
                                                                                                              CMS
   PLAN        SEGMENT                                                     TRANSACTION       PART D        APPROVAL        EFFECTIVE
    ID           ID        VERSION       PLAN NAME         PLAN TYPE          TYPE          PREMIUM          DATE            DATE
------------------------------------------------------------------------------------------------------------------------------------
<S>            <C>         <C>          <C>               <C>              <C>              <C>           <C>             <C>

    001           0           3         HealthSpring       Medicare          INITIAL         25.73        08/31/2005      01/01/2006
                                        Prescription      Prescription
                                          Drug Plan         Drug Plan
------------------------------------------------------------------------------------------------------------------------------------
</Table>

/s/ Deke Ellwanger                                 9/7/05
------------------------------------               -----------------------------
CEO:                                               DATE:
Deke Ellwanger
President
44 Vantage Way, Suite 300
Nashville, TN  37228
615-291-7000

/s/ Kevin Bailey                                   9/7/05
------------------------------------               -----------------------------
CFO:                                               DATE:
Kevin Bailey
Chief Financial Officer
44 Vantage Way, Suite 300
Nashville, TN  37228
615-291-7000

                                       14<PAGE>
                                                                   EXHIBIT 10.29

CONTRACT WITH APPROVED ENTITY PURSUANT TO SECTIONS 1860D-1 THROUGH 1860D-42 OF
THE SOCIAL SECURITY ACT FOR THE OPERATION OF A VOLUNTARY MEDICARE PRESCRIPTION
DRUG PLAN

                                     Between

   Centers for Medicare & Medicaid Services (hereinafter referred to as "CMS")

                                       And

               HEALTHSPRING, INC. D/B/A/ HEALTHSPRING OF ILLINOIS
                                     (S5578)

(a Prescription Drug Plan Sponsor, hereinafter referred to as the "PDP Sponsor")

     CMS and the PDP Sponsor, an entity that has been determined eligible to
operate a Voluntary Medicare Prescription Drug Plan by the Administrator of CMS
under 423 CFR Section 423.503, agree to the following for the purposes of
sections 1860D-1 through 1860D-42 (with the exception of sections 1860D-22(a)
and 1860D-31) of the Social Security Act (hereinafter referred to as "the Act").

                                   ARTICLE I.
                  MEDICARE VOLUNTARY PRESCRIPTION DRUG BENEFIT

A.   PDP Sponsor agrees to operate one or more Medicare Voluntary Prescription
     Drug Plans (hereinafter referred to as a "PDP"), as described in its
     application and related materials, including but not limited to all the
     attestations contained therein and a supplemental guidance, for Medicare
     approval and in compliance with the provisions of this contract, which
     incorporates in its entirety the Solicitation For Applications from
     Prescription Drug Plans released on January 21, 2005 (as revised on March
     9, 2005) (hereinafter collectively referred to as "the contract"). The PDP
     Sponsor also agrees to operate in accordance with the regulations at 42 CFR
     Section 423.1 through 42 CFR Section 423.910 (with the exception of
     Subparts Q, R and S), sections 1860D-1 through 1860D-42 (with the exception
     of sections 1860D-22(a) and 1860D-31) of the Social Security Act, and the
     solicitation, as well as all other applicable Federal statutes, regulations
     and policies. This contract is deemed to incorporate any changes that are
     required by statute to be implemented during the term of this contract and
     any regulations or policies implementing or interpreting such statutory
     provisions.

B.   CMS agrees to perform its obligations to the PDP Sponsor consistent with
     the regulations at 42 CFR Section 423.1 through 42 CFR Section 423.910
     (with the exception of Subparts Q, R and S), sections l860D-1 through
     1860D-42 of the Social Security Act (with the exception of

<PAGE>

     sections 1860D-22(a) and 1860D-31) and the solicitation, as well as all
     other applicable Federal statutes, regulations and policies.

C.   CMS agrees that it will not implement, other than at the beginning of a
     calendar year, regulations under 42 CFR Part 423 that impose new,
     significant regulatory requirements on the PDP Sponsor. This provision does
     not apply to new requirements mandated by statute.

D.   This contract is in no way intended to supersede or modify 42 CFR Part 423.
     Failure to reference a regulatory requirement in this contract does not
     affect the applicability of such requirements to the PDP Sponsor and CMS.

                                  ARTICLE II.
                  FUNCTIONS TO BE PERFORMED BY THE PDP SPONSOR

A.   ENROLLMENT

     1.   PDP Sponsor agrees to accept new enrollments, make enrollments
          effective, process voluntary disenrollments and limit involuntary
          disenrollments, as described in 42 CFR, Part 423, Subpart B.

     2.   PDP Sponsor agrees to comply with the prohibition in 42 CFR 423.104(b)
          on discrimination in beneficiary enrollment.

B.   PRESCRIPTION DRUG BENEFIT

     1.   PDP Sponsor agrees to provide the basic prescription drug coverage as
          defined under 42 CFR Section 423.100 and, to the extent applicable,
          supplemental benefits as defined in 42 CFR Section 423.100 and in
          accordance with Subpart C of 42 CFR Part 423. PDP Sponsor also agrees
          to provide Part D benefits as described in the PDP Sponsor's bid(s)
          approved each year by CMS (as referenced in Attachment A, to be
          replaced each year upon renewal of the contract to reflect the
          Sponsor's approved bids for the succeeding contract year).

     2.   PDP Sponsor agrees to calculate and collect beneficiary premiums in
          accordance with 42 CFR Sections 423.286 and 423.293.

C.   DISSEMINATION OF PLAN INFORMATION

     1.   PDP Sponsor agrees to provide the information required in 42 CFR
          Section 423.48.

     2.   PDP Sponsor agrees to disclose information to beneficiaries in the
          manner and the form specified by CMS under 42 CFR Sections 423.128,
          423.50 and in the "Marketing Materials Guidelines for Medicare
          Advantage-Prescription Drug Plans (MA-PDs) and Prescription Drug Plans
          (PDPs)," and to comply with requirements in 42 CFR Section 423.50
          requiring certain approvals of marketing materials prior to
          distribution.

                                       2
<PAGE>

     3.   PDP Sponsor certifies that all materials it submits to CMS under the
          File and Use Certification authority described in the Marketing
          Materials Guidelines are accurate, truthful, not misleading and
          consistent with CMS marketing guidelines.

D.   QUALITY ASSURANCE/UTILIZATION MANAGEMENT

     PDP Sponsor agrees to operate quality assurance, drug utilization
     management and medication therapy management programs, and to support
     electronic prescribing in accordance with Subpart D of 42 CFR Part 423.

E.   APPEALS AND GRIEVANCES

     PDP Sponsor agrees to comply with all requirements in Subpart M of 42 CFR
     Part 423 governing coverage determinations, grievances and appeals, and
     formulary exceptions.

F.   PAYMENT TO PDP SPONSOR

     1.   PDP Sponsor and CMS agree that payment under this contract will be
          governed by the rules in Subpart G of 42 CFR Part 423.

     2.   If the PDP Sponsor is participating in the Part D Reinsurance Payment
          Demonstration, described in 70 FR 9360 (Feb. 25, 2005) it affirms that
          it will not seek payment under the demonstration for services provided
          to employer group enrollees.

     3.   PDP Sponsor agrees that it is bound by all applicable federal laws and
          regulations, guidance, and authorities pertaining to claims and debt
          collections. In the event that the government determines that the PDP
          Sponsor has been overpaid, the PDP Sponsor agrees to return those
          overpaid monies back to the federal government.

G.   BID SUBMISSION AND REVIEW

     If the PDP Sponsor intends to participate in the Part D program for the
     next program year, PDP Sponsor agrees to submit the next year's bid,
     including all required information on premiums, benefits and cost-sharing,
     by the applicable due date, as provided in Subpart F of 42 CFR Part 423 so
     that CMS and the Part D plan sponsor may conduct negotiations regarding the
     terms and conditions of the proposed bid and benefit plan renewal.

H.   STATE LAW AND LICENSURE REQUIREMENTS

     1.   PDP Sponsor agrees to comply with State law to the extent that it is
          not preempted by Federal law as described in Subpart I of 42 CFR Part
          423.

                                       3
<PAGE>

     2.   PDP Sponsor agrees that where it is operating in a State using a
          waiver granted pursuant to 42 CFR Section 423.410, such waiver shall
          be valid for three consecutive program years. PDP Sponsor agrees that
          expiration of the licensure waiver (and the failure to obtain a
          license from the relevant State) may be the basis for CMS deleting
          from the PDP Sponsor's service area those PDP Regions affected by the
          waiver expiration. CMS may terminate or non-renew the PDP Sponsor's
          contract where the expiration of the waiver results in the PDP Sponsor
          not being qualified to offer a PDP plan in any PDP Region.

     3.   PDP Sponsor agrees that where it is operating in a State using a
          waiver granted pursuant to 42 CFR Section 423.415, such waiver shall
          be valid for the period that the Secretary of the Department of Health
          and Human Services determines is appropriate for timely processing of
          the PDP Sponsor's license application by the State, but in no case no
          more than one year only, beginning on January 1 of the contract year
          for which CMS granted the waiver.

I.   COORDINATION WITH OTHER PRESCRIPTION DRUG COVERAGE

     1.   PDP Sponsor agrees to comply with the coordination requirements with
          State Pharmacy Assistance Programs (SPAPs) and plans that provide
          other prescription drug coverage as described in Subpart J of 42 CFR
          Part 423.

     2.   PDP Sponsor agrees to comply with Medicare Secondary Payer procedures
          as stated in 42 CFR Section 42.462.

J.   SERVICE AREA AND PHARMACY ACCESS

     1.   The PDP Sponsor agrees to provide Part D benefits in the service area
          for which it has been approved by CMS utilizing a pharmacy network and
          formulary approved by CMS that meet the requirements of 42 CFR Section
          423.120.

     2.   The PDP Sponsor agrees to provide Part D benefits through
          out-of-network pharmacies according to 42 CFR Section 423.124.

     3.   PDP Sponsor agrees to provide benefits by means of point of service
          systems to adjudicate prescription drug claims in a timely and
          efficient manner in compliance with CMS standards, except when
          necessary to provide access in underserved areas, I/T/U pharmacies (as
          defined in 42 CFR Section 423.100), and long-term care pharmacies (as
          defined in 42 CFR Section 423.100).

     4.   PDP Sponsor agrees to contract with any pharmacy that meets the PDP
          Sponsor's reasonable and relevant standard terms and conditions.

                                       4
<PAGE>

K.   COMPLIANCE PLAN/PROGRAM INTEGRITY

     1.   PDP Sponsor agrees that it will develop and implement a compliance
          plan that applies to its Part D-related operations, consistent with 42
          CFR Section 423.504(b)(4)(vi).

     2.   The PDP sponsor agrees to provide notice based on best knowledge,
          information and belief to CMS of any integrity items related to
          payments from governmental entities, both federal and state, for
          healthcare or prescription drug services that would have been reported
          as part of 3.1.4 of the PDP application. These items include any
          investigations, legal actions or matters subject to arbitration
          brought involving the sponsor (or sponsor's firm if applicable) and
          its subcontractors (excluding contracted network providers), including
          any key management or executive staff or any major shareholders (5% or
          more), by a government agency (state or federal) on matters relating
          to payments from governmental entities, both federal and state, for
          healthcare and/or prescription drug services. In providing the notice,
          the sponsor shall keep the government informed of when the integrity
          item is initiated and when it is closed. Notice should be provided of
          the details concerning any resolution and monetary payments as well as
          any settlement agreements or corporate integrity agreements.

     3.   The PDP Sponsor agrees to provide notice based on best knowledge,
          information and belief to CMS in the event the Sponsor or any of its
          subcontractors is criminally convicted or has a civil judgment entered
          against it for fraudulent activities or is sanctioned under any
          Federal program involving the provision of health care or prescription
          drug services.

L.   LOW-INCOME SUBSIDY

     PDP Sponsor agrees that it will participate in the administration of
     subsidies for low-income individuals according to Subpart P of 42 CFR Part
     423.

M.   COMMUNICATION WITH CMS

     PDP Sponsor agrees that it shall maintain the capacity to communicate with
     CMS electronically in accordance with CMS requirements.

N.   BENEFICIARY FINANCIAL PROTECTIONS

     The PDP Sponsor agrees to afford its enrollees protection from liability
     for payment of fees that are the obligation of the PDP Sponsor in
     accordance with 42 CFR Section 423.505(g).

                                       5
<PAGE>

O.   RELATIONSHIP WITH RELATED ENTITIES, CONTRACTORS AND SUBCONTRACTORS

     1.   The PDP Sponsor agrees it maintains ultimate responsibility for
          adhering to and otherwise fully complying with all terms and
          conditions of this contract with CMS.

     2.   The PDP Sponsor shall ensure that any contracts or agreements with
          subcontractors or agents performing functions on the PDP Sponsor's
          behalf related to the operation of the Part D benefit are in
          compliance with 42 CFR Section 423.505(i).

     3.   The PDP Sponsor agrees to act in accordance with 45 CFR Part 76 and
          agrees that it will not contract with or employ entities or
          individuals that are excluded by the Department of Health and Human
          Services, Office of the Inspector General or included on the Excluded
          Parties List System maintained by the General Services Administration.

P.   CERTIFICATION OF DATA THAT DETERMINE PAYMENT

     PDP Sponsor must provide certifications in accordance with 42 CFR Section
     423.505(k).

Q.   ENROLLMENT RELATED COSTS

     PDP Sponsor agrees to payment of fees established by CMS for cost sharing
     of enrollment related costs in accordance with 42 CFR Section 423.6.

                                  ARTICLE III.
                   RECORD RETENTION AND REPORTING REQUIREMENTS

A.   RECORD MAINTENANCE AND ACCESS

     PDP Sponsor agrees to maintain records and provide access in accordance
     with 42 CFR Sections 423.504(d), and 423.505(d) and (e).

B.   GENERAL REPORTING REQUIREMENTS

     The PDP Sponsor agrees to submit information to CMS according to 42 CFR
     Sections 423.505(f), 423 .514 and the "Final Medicare Part D Reporting
     Requirements," a document issued by CMS and subject to modification each
     program year.

C.   LICENSURE-RELATED REPORTING REQUIREMENTS

     1.   If the PDP Sponsor is operating under a CMS-granted licensure waiver
          in any State, the PDP Sponsor agrees to notify CMS in writing of the
          State's disposition

                                       6
<PAGE>

          of the Sponsor's license application within ten (10) business days of
          the date that it receives notice of the State's action.

     2.   For those States where the PDP Sponsor is operating under a
          risk-bearing license, the Sponsor agrees to provide written notice to
          CMS of the State's non-renewal of the Sponsor's license within ten
          days of receiving notice of the State's action.

     3.   In the event that a State regulator imposes a sanction against the PDP
          Sponsor or requires the implementation of a corrective action plan,
          the Sponsor agrees to provide written notice to CMS of such sanction
          or corrective action requirement (including basis for the sanction
          and/or timeline for corrective action) within ten days of receiving
          notice of the State's action.

     4.   In the event that there is a change in the status of the PDP Sponsor's
          risk-bearing license in any State (e.g., suspension, revocation), the
          Sponsor agrees to provide written notice to CMS of the change in
          status (including basis for the change in status and effective date)
          within ten (10) days of receiving notice of the State's action.

     5.   If the PDP Sponsor is operating a Part D benefit under a CMS-granted
          waiver in every State in its service area, and the Sponsor is
          terminating or reducing the amount of an existing letter of credit
          obtained for the purposes of funding projected losses, the Sponsor
          shall provide written notice to CMS of such action thirty (30) days
          prior to its effective date. The PDP Sponsor agrees that it must
          obtain CMS approval prior to terminating or reducing the amount of a
          letter of credit obtained for the purposes of funding projected losses
          under Appendix X of the PDP Solicitation.

D.   CMS LICENSE FOR USE OF PLAN FORMULARY

     PDP Sponsor agrees to submit to CMS each plan's formulary information,
     including any changes to its formularies, and hereby grants to the
     Government [, and any person or entity who might receive the formulary from
     the Government,] a non-exclusive license to use all or any portion of the
     formulary for any purpose related to the administration of the Part D
     program, including without limitation publicly distributing, displaying,
     publishing or reconfiguration of the information in any medium, including
     www.medicare.gov, and by any electronic, print or other means of
     distribution.

                                  ARTICLE IV.
                                HIPAA PROVISIONS

                       HIPAA TRANSACTIONS/PRIVACY/SECURITY

A.   PDP Sponsor agrees to comply with the confidentiality and enrollee record
     accuracy requirements specified in 42 CFR Section 423.136.

                                       7
<PAGE>

B.   PDP Sponsor agrees to enter into a business associate agreement with the
     entity with which CMS has contracted to track Medicare beneficiaries' true
     out-of-pocket costs.

                                   ARTICLE V.
                   REQUIREMENTS OF OTHER LAWS AND REGULATIONS

     The PDP Sponsor agrees to comply with (a) applicable Federal laws and
regulations designed to prevent fraud, waste and abuse, including, but not
limited to applicable provisions of Federal criminal law, the False Claims Act
(31 U.S.C. Sections 3729 et seq.), and the anti-kickback provision of section
1128B of the Act; (b) applicable HIPAA Administrative Simplification Security
and Privacy rules at 45 CFR parts 160, 162 and 164; and (c) all other applicable
Federal statutes and regulations.

                                  ARTICLE VI.
                            CONTRACT TERM AND RENEWAL

A.   TERM OF CONTRACT

     This contract is effective from the date of CMS' authorized
     representative's signature through December 31, 2006. This contract shall
     be renewable for successive one-year periods thereafter according to 42 CFR
     Section 423.506. PDP Sponsor shall not conduct Part D-related marketing
     activities prior to October 1, 2005 and shall not process enrollment
     applications prior to November 15, 2005. PDP Sponsor shall begin delivering
     prescription drug benefit services on January 1, 2006.

B.   QUALIFICATION TO RENEW A CONTRACT

     1.   In accordance with 42 CFR Section 423.507, the PDP Sponsor will be
          determined qualified to renew its contract annually only if:

          (a)  CMS informs the PDP Sponsor that it is qualified to renew its
               contract; and

          (b)  The PDP Sponsor has not provided CMS with a notice of intention
               not to renew in accordance with Article VII of this contract.

     2.   Although PDP Sponsor may be determined qualified to renew its contract
          under this Article, if the PDP Sponsor and CMS cannot reach agreement
          on the bid under Subpart F of 42 CFR Part 423, no renewal takes place,
          and the failure to reach agreement is not subject to the appeals
          provisions in Subpart N of 42 CFR Part 423.

                                       8
<PAGE>

                                  ARTICLE VII.
                             NONRENEWAL OF CONTRACT

A.   NONRENEWAL BY THE PDP SPONSOR

     1.   The PDP Sponsor may elect not to renew its contract with CMS,
          effective at the end of the term of the contract for any reason as
          long as PDP Sponsor provides proper notice of the decision according
          to the required timeframes.

     2.   If the PDP Sponsor does not intend to renew its contract, it must
          notify:

          (a)  CMS in writing by the first Monday of June in the year in which
               the current contract period ends;

          (b)  Each Medicare enrollee, at least ninety (90) days before the date
               on which the nonrenewal is effective. This notice must include a
               written description of alternatives available for obtaining
               qualified prescription drug coverage within the PDP region,
               including Medicare Advantage-Prescription Drug plans, Medicare
               cost plans offering a Part D plan, and other PDPs, and must
               receive CMS approval prior to issuance; and

          (c)  The general public, at least ninety (90) days before the end of
               the current calendar year, by publishing a notice in one or more
               newspapers of general circulation in each community or county
               located in the Part D plan sponsor's service area.

     3.   If the PDP Sponsor does not renew a contract, CMS cannot enter into a
          contract with the organization for two (2) years unless there are
          special circumstances that warrant special consideration, as
          determined by CMS.

     4.   If the PDP Sponsor does not renew a contract, it must ensure the
          timely transfer of any data or files in accordance with CMS
          instructions.

B.   NONRENEWAL BY CMS

     1.   CMS may determine that the PDP Sponsor is not qualified to renew its
          contract for any of the following reasons:

          (a)  The reasons listed in 42 CFR Section 423.509(a) that also permit
               CMS to terminate the contract.

          (b)  The PDP Sponsor has committed any of the acts in 42 CFR Section
               423.752 that support the imposition of intermediate sanctions or
               civil money penalties under 42 CFR Section 423.750.

     2.   CMS will provide notice of its decision whether the PDP Sponsor is
          qualified to renew its contract as follows:

               (i)  To the PDP Sponsor by May 1 of the current contract year.

                                       9
<PAGE>

               (ii) If CMS decides that the PDP Sponsor is not qualified to
                    renew its contract, to the PDP Sponsor's Medicare enrollees
                    by mail at least ninety (90) days before the end of the
                    current calendar year.

              (iii) If CMS determines that the PDP Sponsor is not qualified to
                    renew its contract, to the general public at least ninety
                    (90) days before the end of the current calendar year, by
                    publishing a notice in one (1) or more newspapers of general
                    circulation in each community or county located in the PDP
                    Sponsor's service area.

               (iv) CMS will provide the notice described in (B)(2)(ii) and
                    (iii) of this Article where a non-renewal results because
                    CMS and the PDP Sponsor are unable to reach agreement on the
                    bid under 42 CFR Part 423, Subpart F.

     3.   CMS shall give the PDP Sponsor written notice of its right to appeal
          the decision that the sponsor is not qualified renew its contract in
          accordance with 42 CFR Section 423.642(b).

                                 ARTICLE VIII.
                     MODIFICATION OR TERMINATION OF CONTRACT

A.   CONTRACT MODIFICATION OR TERMINATION BY MUTUAL CONSENT

     1.   This contract may be modified or terminated at any time by written
          mutual consent of the parties.

     2.   If this contract is terminated by mutual consent, the PDP Sponsor must
          provide notice to its Medicare enrollees and the general public in
          accordance with CMS's instructions.

     3.   If the contract is modified by mutual consent, the PDP Sponsor must
          notify its Medicare enrollees of any changes that CMS determines are
          appropriate for notification according to the process and timeframes
          specified by CMS.

     4.   If a contract is terminated under section A of this Article, the PDP
          Sponsor must ensure the timely transfer of any data or files.

B.   TERMINATION OF CONTRACT BY CMS

     CMS may terminate the contract in accordance with 42 CFR Section 423.509.

C.   TERMINATION OF CONTRACT BY THE PDP SPONSOR

     The PDP Sponsor may terminate the contract only in accordance with 42 CFR
Section 423.510.

                                       10
<PAGE>

                                  ARTICLE IX.
                             INTERMEDIATE SANCTIONS

     Consistent with Subpart O of 42 CFR Part 423, the PDP Sponsor shall be
subject to sanctions and civil money penalties.

                                   ARTICLE X.
                                  SEVERABILITY

     Severability of the contract shall be in accordance with 42 CFR 423.504(e).

                                   ARTICLE XI.
                                  MISCELLANEOUS

A.   DEFINITIONS

     Terms not otherwise defined in this contract shall have the meaning given
     to such terms in 42 CFR Part 423.

B.   ALTERATION TO ORIGINAL CONTRACT TERMS

     The PDP Sponsor agrees that it has not altered in any way the terms of the
     PDP contract presented for signature by CMS. PDP Sponsor agrees that any
     alterations to the original text the PDP Sponsor may make to this contract
     shall not be binding on the parties.

C.   ADDITIONAL CONTRACT TERMS

     The PDP Sponsor agrees to include in this contract other terms and
     conditions in accordance with 42 CFR Section 423.505(j).

D.   CMS APPROVAL TO BEGIN MARKETING AND ENROLLMENT ACTIVITIES

     PDP Sponsor agrees that it must complete CMS operational requirements prior
     to receiving CMS approval to begin Part D marketing and enrollment
     activities. Such activities include, but are not limited to, establishing
     and successfully testing connectivity with CMS systems to process
     enrollment applications (or contracting with an entity qualified to perform
     such functions on PDP Sponsor's behalf) and successfully demonstrating
     capability to submit accurate and timely price comparison data. To
     establish and successfully test connectivity, the PDP Sponsor must, 1)
     establish and test physical connectivity to the CMS data center, 2) acquire
     user identifications and passwords, 3) receive, store and maintain data
     necessary to perform enrollments and send and receive transactions to and
     from CMS, and 4) check and receive transaction status information.

                                       11
<PAGE>

     IN WITNESS WHEREOF, the parties hereby execute this contract.

FOR THE PDP SPONSOR:

JEFF ROTHENBERGER                           SR. VP & CORPORATE COO
--------------------------------------------------------------------------------
Printed Name                                Title

/s/ Jeff Rothenberger                                     9/7/05
--------------------------------------------------------------------------------
Signature                                                  Date

HEALTHSPRING, INC. D/B/A HEALTHSPRING OF ILLINOIS
----------------------------------------------------
Organization

9701 WEST HIGGINS RD., SUITE 360, ROSEMONT, IL 60018
-----------------------------------------------------
Address

FOR THE CENTERS FOR MEDICARE & MEDICAID SERVICES:

/s/ Robert Donnelly                                       10/11/05
--------------------------------------------------------------------------------
Robert Donnelly                                           Date
Director Medicare Drug Benefit Group
Center for Beneficiary Choices

                                       12

<PAGE>

                                  ATTACHMENT A

                      PART D BENEFIT PLAN(S) -- DESCRIPTION

                                       13

<PAGE>

          Prescription Drug Plan Attestation of Benefit Plan and Price

                               HEALTHSPRING, INC.

                                      S5578

                                Date: 09/06/2005

I attest that the following plan numbers as established in the final Plan
Benefit Package (PBP) will be operated by the above-stated organization and made
available to eligible Medicare beneficiaries In the approved service area during
program year 2006.

<Table>
<Caption>
------------------------------------------------------------------------------------------------------------------------------
  PLAN        SEGMENT      VERSION      PLAN NAME        PLAN TYPE      TRANSACTION      PART D          CMS         EFFECTIVE
   ID           ID                                                          TYPE         PREMIUM      APPROVAL         DATE
                                                                                                        DATE
------------------------------------------------------------------------------------------------------------------------------
<S>           <C>          <C>         <C>              <C>             <C>              <C>         <C>            <C>
                                       HealthSpring       Medicare
   001           0            4        Prescription     Prescription      Initial         24.78      09/06/2005     01/01/2006
                                        Drug Plan        Drug Plan
------------------------------------------------------------------------------------------------------------------------------
</Table>

/s/ Randy Fike                                              10/5/05
----------------------------------------             ---------------------------
CEO:                                                 DATE:
Randy Fike
President
9701 West Higgins Road Suite 360
Chicago, IL 60018
847-993-1900

/s/ Randy Fike                                              10/5/05
----------------------------------------             ---------------------------
CFO:                                                 DATE:
Randy Fike
CFO
9701 West Higgins Road Suite 360
Chicago, IL 60018
847-993-1900

                                       14

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