<PAGE>
                                                                 EXHIBIT 10.18

                              EMPLOYMENT AGREEMENT

         This EMPLOYMENT AGREEMENT (the "Agreement") is made and entered into as
of December 1, 2003 by and between AHS Management Company, Inc., a Delaware
corporation ("the Company"), and R. Dirk Allison, an individual ("Employee").

                                   WITNESSETH:

         WHEREAS, the Company desires to enter into this Agreement with Employee
and to provide him with the benefits set forth herein in recognition of the
valuable services he will render to the Company, and for the purposes evidenced
herein;

         WHEREAS, Employee is ready and willing to render the services provided
for, and on the terms and conditions set forth herein, and he is willing to
refrain from activities competitive with the business of the Company during the
term and after of this Agreement on the terms and conditions set forth herein;

         WHEREAS, in serving as an employee of the Company, Employee will
participate in the use and development of confidential proprietary information
about the Company, its customers and suppliers, and the methods used by the
Company and its employees in competition with other companies, as to which the
Company desires to protect fully its rights;

         NOW, THEREFORE, in consideration of the premises and the mutual
covenants and agreements herein set forth, the parties hereto agree as follows:

         1.       Employment. The Company hereby employs Employee and Employee
accepts such employment with the Company, subject to the terms and conditions
set forth herein. Employee shall be employed as Executive Vice President and
Chief Financial Officer and shall perform all duties and services incident to
such position, and such other similar duties and services as may be prescribed
by the Bylaws of the Company or established by the Chairman of the Board of
Directors or Chief Executive Officer of the Company, or its parent corporation
from time to time. During his employment hereunder, Employee shall devote his
best efforts and attention, on a full-time basis, to the performance of the
duties required of him as an employee of the Company.

         2.       Principal Office. Employee's principal office and normal place
of work shall be at the Company's principal executive offices in Nashville,
Tennessee ("Principal Office").

         3.       Compensation.

                  (a)      As compensation for services rendered by Employee
hereunder, Employee shall receive:

                           (1)      Salary. An annual salary of $400,000.00, or
such higher salary as shall be approved by the Board of Directors of the Company
("the Board") from time to time, which shall be payable in arrears in equal
monthly installments ("Salary").

                           (2)      Bonus. The Company shall pay Employee an
annual cash bonus in an amount to be determined by the Board based on whether
certain reasonable objectives established by the


                                       1
<PAGE>



Board prior to the beginning of each Fiscal Year as set forth in the Company's
Incentive Compensation Plan have been met. Such bonus and objectives may be
stated in a written incentive compensation program which the Company intends to
qualify as "performance based compensation" described in Internal Revenue Code
section 162(m). The bonus payable during the first year, beginning January 1,
2004, shall be 75% of Employee's Salary if the Plan objectives have been met,
and 125% of 75% of Salary if the Plan is met and exceeded by 10% or more.

                           (3)      Fringe Benefits. Employee shall be entitled
during the term of this Agreement to such other benefits of employment with
Employer as are now or may hereafter be in effect for Employer's senior
executives with duties comparable to Employee including, without limitation, all
incentive and deferred compensation, pension, life and other insurance,
disability (insured and uninsured), medical and dental and other benefit plans
or programs, paid time off and stock option grants as approved by the Board of
Directors. Additionally, Employee shall be provided the opportunity to buy
additional life insurance Employee's expense.

                           (4)      Expenses. During the term of this Agreement,
Employer shall reimburse Employee promptly for all reasonable travel,
entertainment, parking, business meeting and similar expenditures in pursuance
and furtherance of Employer's business upon receipt of reasonable supporting
documentation as required by Employer's policies applicable to its officers and
other key employees generally. Until May 30, 2004, the Company will pay for (i)
Employee's and Employee's spouse's reasonable weekly travel expenses to/from
Dallas, Texas and Nashville, Tennessee, (ii) all reasonable temporary housing
expenses incurred including utilities and deposits, and (iii) all reasonable
moving expenses associated with Employee's relocation to Nashville on both a
temporary basis and when he permanently moves his residency to Nashville,
Tennessee, provided Employee follows the Company's expense reimbursement and
moving policies when claiming said reimbursement.

                           (5)      Withholdings. All amounts payable to
Employee hereunder shall be subject to such deductions or withholdings as are
required by law or the policies of the Employer or as may be authorized or
directed by Employee.

                  (b)      Benefits Review. Prior to the end of each fiscal year
of the Company, the Board of Directors of the Company shall review Employee's
salary and benefits payable hereunder. Any increases in salary or changes in
fringe benefits determined by the Board of Directors of the Company at such
annual review shall become effective the following month unless otherwise
determined by the Company. Employee understands and acknowledges that the
opportunity of an annual salary and benefit review by the Board shall not be
construed in any manner as an express or implied agreement by the Company to
raise or increase his salary or benefits.

                  (c)      Indemnification. This Agreement hereby incorporates
and makes a part of this agreement the Indemnification Agreement dated
contemporaneously herewith by and between Employee and Ardent Health Services
LLC. The provisions and rights guaranteed under that Agreement shall survive any
termination of this Agreement.

                  (d)      Employee Acceptance Bonus. Company will pay Employee
a total amount of $700,000.00, subject to appropriate withholdings, as a
one-time employment acceptance bonus.


                                       2
<PAGE>

         4.       Confidential Information and Trade Secrets.

                  (a)      Trade Secrets. Employee recognizes that Employee's
position with the Company requires considerable responsibility and trust, and,
in reliance on Employee's loyalty, the Company may entrust Employee with highly
sensitive confidential, restricted and proprietary information involving Trade
Secrets and Confidential Information. For purposes of this Agreement, a "Trade
Secret" is any scientific or technical information, design, process, procedure,
formula or improvement that is valuable and not generally known to competitors
of the Company. "Confidential Information" is any data or information, other
than Trade Secrets, that is important, competitively sensitive, and not
generally known by the public, including, but not limited to, the Company's
business plan, acquisition targets, training manuals, product development plans,
pricing procedures, market strategies, internal performance statistics,
financial data, confidential personnel information concerning employees of the
Company, supplier data, operational or administrative plans, policy manuals, and
terms and conditions of contracts and agreements. The terms "Trade Secret" and
"Confidential Information" shall not apply to information which is (i) made
available to the general public without restriction by the Company, (ii)
obtained from a third party by Employee in the ordinary course of Employee's
employment by the Company, or (iii) required to be disclosed by Employee
pursuant to subpoena or other lawful process, provided that Employee notifies
the Company in a timely manner to allow the Company to appear to protect its
interests.

                  (b)      Non-disclosure. Except as required to perform
Employee's duties hereunder, Employee will not use or disclose any Trade Secrets
or Confidential Information of the Company during employment, or at any time
after termination of employment and prior to such time as they cease to be Trade
Secrets or Confidential Information through no act of Employee in violation of
this Agreement.

                  (c)      Material Surrender. Upon termination of Employee's
employment with Company, Employee will surrender to the Company all files,
correspondence, memoranda, notes, records, manuals or other documents or data
pertaining to the Company's business or Employee's employment (including all
copies thereof) however prepared and whether maintained in paper or electronic
format. Employee will also leave with the Company all materials involving any
Trade Secrets or Confidential Information of the Company. All such information
and materials, whether or not made or developed by Employee, shall be the sole
and exclusive property of the Company, and Employee hereby assigns to the
Company all of Employee's right, title and interest in and to any and all of
such information and materials.

         5.       Covenants. Employee shall be subject to the following
covenants and obligations:

                  (a)      Non-competition covenant. While employed by the
Company, Employee shall not compete or plan or prepare to compete with the
Company regarding the ownership of, investment in, management of or operation of
free standing hospitals that provide either medical surgical and/or behavioral
healthcare services ("Hospital"). Employee shall not compete with the Company
for a period of three (3) years following the termination of his employment,
within thirty (30) miles of any location where (i) the Company owned, operated
or managed any Hospital either on the date his employment terminates or at any
time within the immediately preceding Fiscal Year or (ii) the Board had approved
the potential or final acquisition of any Hospital prior to his termination and
Employee had knowledge of said approval.

                  (b)      Non-solicitation covenant. Following the termination
of Employee's employment with the Company, for a period equal to the term of the
non-competition covenant under Section 5(a), Employee shall not directly or
indirectly solicit the services of or otherwise induce or attempt to induce any
Company Employee to sever his/her employment relationship with the Company. For
purposes of this


                                       3
<PAGE>

section "Company Employee" shall mean (i) any employee who performs or performed
(on the Termination Date or within the previous six (6) months of such date) any
of his/her services at the Company's Principal Office and (ii) any member of the
senior management staff of any line of hospital based healthcare business owned,
operated or managed by the Company. Prior to the initiation of any conduct
prohibited under this Section, Employee may request that the Company waive
application of this Section to said conduct. Granting of such request, however,
shall be at the Company's sole discretion.

                  (c)      Scope and Duration; Severability. The Company and
Employee understand and agree that the scope and duration of the covenants
contained in this Section 5 are reasonable both in time and geographical area
and are fairly necessary to protect the business of the Company. Except as
otherwise stated herein, such covenants shall survive the termination of
Employee's employment. It is further agreed that such covenants shall be
regarded as divisible and shall be operative as to time and geographical area to
the extent that they may be made so and, if any part of such covenants are
declared invalid or unenforceable, the validity and enforceability of the
remainder shall not be affected.

                  (d)      Assignment. Employee agrees that the covenants
contained in this Section 5 shall inure to the benefit of any successor or
assign of the Company, with the same force and effect as if such covenant had
been made by Employee with such successor or assign.

                  (e)      Exclusion. Notwithstanding the provisions of this
Section 5, Employee's non-competition obligations shall not preclude Employee
from owning one percent (1%) or less of the voting power or common interest in
any publicly traded corporation conducting business activities in the healthcare
industry in competition with the Company or any affiliate.

                  (f)      Company. For purposes of this section 5, "Company"
shall mean Ardent Health Services LLC, Ardent Health Services, Inc., AHS
Management Company, Inc., Ardent Medical Services, Inc., and/or Behavioral
Healthcare Corporation.

         6.       Program Participation. Employee represents that he is, and
will for the term of this Agreement be eligible to participate in Medicare,
Medicaid, CHAMPUS, Tri-Care, and other federal health programs, and Employee
shall not have been sanctioned by the Health and Human Services Office of the
Inspector General, Cumulative Sanctions Report, or excluded by the General
Services Administration, as set forth on the List of Excluded Providers [see
www.dbhs.gov/progorg/org and www.arnet.gov/epis].

         7.       Specific Enforcement. Employee specifically acknowledges and
agrees that the restrictions set forth in Sections 4 and 5 hereof are reasonable
and necessary to protect the legitimate interests of the Company and that the
Company would not have entered into this Agreement in the absence of such
restrictions. Employee further acknowledges and agrees that any violation of the
provisions of Section 4 and 5 hereof will result in irreparable injury to the
Company, that the remedy at law for any violation or threatened violation of
such Sections will be inadequate and that in the event of any such breach, the
Company, in addition to any other remedies or damages available to it at law or
in equity, shall be entitled to temporary injunctive relief before trial from
any court of competent jurisdiction as a matter of course and to permanent
injunctive relief without the necessity of proving actual damages. The Company
shall also have available all remedies provided under state and federal
statutes, rules and regulations as well as any and all other remedies as may
otherwise be contractually or equitably available. In addition to any other
remedy herein granted or available to Company, either at law or in equity,
Employee shall forfeit and forever release any claim or right Employee may have
to any benefits remaining under this Agreement from the date Employee breached
section 5 of this Agreement. Any monetary damages sought by Company under this


                                       4
<PAGE>

section shall not include the benefits forfeited under this section.

         8.       Term. This Agreement shall continue for three (3) years from
the date first written above ("Initial Term"), unless sooner terminated in the
manner set forth herein; provided, however, that following the Initial Term,
this Agreement shall automatically renew at the end of the Initial Term for
additional terms of one (1) year (collectively "the Term") unless either party
gives notice of termination to the other not later than thirty (30) days prior
to the annual anniversary of the end of the Initial Term (a "Notice of Non-
Renewal"). The date upon which this Agreement and Employee's employment
hereunder shall terminate, whether pursuant to the terms of this Section or
pursuant to any other provision of this Agreement shall hereafter be referred to
as the "Termination Date."

         9.       Non-renewal Termination. In the event this Agreement
terminates pursuant to a Notice of Non-Renewal, the Company shall have no
further obligation to Employee and Employee shall have no further rights or
obligations hereunder except that the Company shall be obligated to pay
Employee, as severance compensation, the salary and benefits set forth in
Sections 13(b) and (c) of this Agreement. Employee's obligations under Section 4
hereof shall survive the termination of this Agreement pursuant to a Notice of
Non-renewal by either party. Employee's obligations under Section 5 hereof shall
only apply for twelve (12) months if the Company is the non-renewing party, but
shall continue in full force and effect if Employee is the non-renewing party.

         10.      Termination upon Death of the Employee. In the event the
Employee dies during the term of this Agreement, this Agreement shall
immediately terminate and neither the Employee nor the Company shall have any
further obligations hereunder, except that the Company shall continue to pay
Employee's estate his salary and benefits, in effect immediately prior to the
Termination Date, set forth in Section 3(a) of this Agreement, for the
remaining term of this Agreement.

         11.      Termination by the Company for Cause. The Company shall have
the right at any time to terminate Employee's employment immediately for cause.
The term "Cause" shall mean (i) Employee's willful refusal to perform the
reasonable duties of Employee's office delegated under Section 1 of this
Agreement, (ii) Employee's conviction of any crime punishable as a felony or
involving moral turpitude or fraud, or (iii) Employee's change in status under
Section 6 of this Agreement. Employee's obligations under Sections 4 and 5
hereof shall survive in full force and effect the termination of the Agreement
pursuant to this Section 11. In the event Employee's employment hereunder is
terminated in accordance with this Section, the Company shall have no further
obligation to make any payments to Employee hereunder except for unpaid salary
or unreimbursed expenses that have accrued but have not been paid as of the
Termination Date.

         12.      Termination without Cause.


                  (a)      In the event that Employee is terminated by the
Company without cause during the term hereof (which shall not include a
termination pursuant to Sections 9, 10, 11, 13, or 14,), the Company shall: (a)
pay Employee all bonuses and unreimbursed expenses owed to Employee that have
been incurred, but have not been paid as of the Termination Date; and (b) pay to
Employee, as severance compensation, the salary and benefits set forth in
Sections 13(b) and (c) of this Agreement. Employee's obligations under Section 4
hereof shall survive the termination of this Agreement pursuant to this Section.
In the event of a termination pursuant to this section, Section 5 shall apply in
full force and effect for only twelve (12) months from the Termination Date.

                  (b)      In the event that Employee terminates his employment
with the Company


                                       5
<PAGE>

without cause during the term hereof (which shall not include a termination
pursuant to Sections 9, 10, 11, 13, or 14), the Company shall only be obligated
to pay Employee any salary and unreimbursed expenses owed to Employee that have
been incurred but have not been paid as of the Termination Date. Employee's
obligations under Sections 4 and 5 hereof shall survive in full force and effect
the termination of the Agreement pursuant to this Section 12(b).

         13.      Termination upon a Change in Control. Employee shall have the
unilateral right, to be exercised or not in his sole discretion, to terminate
this Agreement under this Section 14 within one hundred eighty (180) days after
a Change in Control (as such term is hereinafter defined). Notwithstanding any
statement contained in this Agreement to the contrary (other than in Section
11), in the event of Employee's termination of employment for any reason within
one hundred eighty (180) days following a Change in Control, Employee shall be
entitled to the compensation and benefits described in Section 13(b) and (c).
Employee's obligations under Sections 4 and 5 hereof shall survive in full force
and effect the termination of the Agreement pursuant to this Section 13.

                  (a)      For purposes of this Agreement, a Change in Control
means the occurrence of any of the following events, provided that references to
the Company in this Section 13(a) shall be treated as a reference solely to AHS
Management Company, Inc., Ardent Health Services, Inc., and/or Ardent Health
Services LLC.

                           (1)      An acquisition (other than (i) directly from
the Company or (ii) by any Principal or a Related Party of a Principal) of any
voting securities of the Company (the "Voting Securities") by any "Person" (as
that term is used for purposes of Section 13(d) or 14(d) of the Securities
Exchange Act of 1934, as amended (the "Exchange Act")), immediately after which
such Person has "Beneficial Ownership" (within the meaning of Rule 13d-3
promulgated under the Exchange Act) of more than fifty percent (50%) of the
combined voting power of the Company's then outstanding voting Securities;
provided, however, in determining whether a Change in Control has occurred,
Voting Securities which are acquired in a Non-Control Acquisition shall not
constitute an acquisition which would cause a Change in Control. A "Non-Control
Acquisition" shall mean an acquisition by (1) an employee benefit plan (or a
trust forming a part thereof) maintained by (A) the Company, or (B) any
corporation or other Person of which a majority of its voting power or its
voting equity securities or equity interest is owned, directly or indirectly, by
the Company (for purposes of this definition, a "Subsidiary"), (2) the Company
or its Subsidiaries, or (3) any person in connection with a Non-Control
Transaction (as hereinafter defined);

                           (2)      The individuals who, as of the date of this
Agreement, are members of the Company's Board of Managers (the "Incumbent
Board"), cease for any reason to constitute at least a majority of the members
of the Company's Board of Managers; provided, however, that if the election, or
nomination for election by the Company's equity holders, of any new Manager was
approved by a vote of at least a majority of the Incumbent Board, such new
Manager shall, for purposes of this Agreement, be considered as a member of the
Incumbent Board; provided, further, however, that no individual shall be
considered a member of the Incumbent Board if such individual initially assumed
office as a result of either an actual or threatened "Election Contest" (as
described in Rule 14a-ll promulgated under the Exchange Act) or other actual or
threatened solicitation of proxies or consents by or on behalf of a Person other
than the Company's Board of Managers (a "Proxy Contest") including by reason of
any agreement intended to avoid or settle any Election Contest or Proxy Contest;
or

                           (3)      Approval by the holders of the Voting
Securities of the Company of:


                                       6
<PAGE>


         (i)      A merger, consolidation or reorganization involving the
                  Company, unless such merger, consolidation or reorganization
                  is a Non-Control Transaction. A "Non-Control Transaction"
                  shall mean a merger, consolidation or reorganization of the
                  Company where:

                  a)       the holders of the Voting Securities of the Company,
                           immediately before such merger, consolidation or
                           reorganization, own directly or indirectly
                           immediately following such merger, consolidation or
                           reorganization, more than fifty percent (50%) of the
                           combined voting power of the outstanding voting
                           securities of the entity resulting from such merger
                           or consolidation or reorganization (the "Surviving
                           Entity") in substantially the same proportion as
                           their own ownership of the Voting Securities
                           immediately before such merger, consolidation or
                           reorganization; and

                  b)       the individuals who were members of the Incumbent
                           Board immediately prior to the execution of the
                           agreement providing for such merger, consolidation or
                           reorganization constitute at least a majority of the
                           members of the board of directors of the Surviving
                           Entity, or a corporation or entity beneficially
                           directly or indirectly owning a majority of the
                           Voting Securities of the Surviving Entity;

         (ii)     A complete liquidation or dissolution of the Company; or

         (iii)    An agreement for the sale or other disposition of all or
                  substantially all of the assets of the Company to any Person
                  (other than a transfer to (i) a Subsidiary or (ii) any
                  Principal or Related Party of a Principal).


For purposes of this Section 14, the following defined terms have the following
meanings:

         "Principals" means (i) Welsh, Carson, Anderson & Stowe, IX, L.P., (ii)
FFC Partners II, L.P., (iii) BancAmerica Capital Investors I, L.P., (iv) any
investment fund under common control or management with any person in the
foregoing clauses (i), (ii) or (iii), and (v) any general partner or other
entity directly controlling or managing any person in the foregoing clauses (i)
through (iv).

         "Related Party " means:

                  (1)      any controlling stockholder, partner, member, 80% (or
         more) owned Subsidiary, or immediate family member (in the case of an
         individual) of any Principal; or

                  (2)      any trust, corporation, partnership or other entity,
         the beneficiaries, stockholders, partners, owners or persons
         beneficially holding an 80% or more controlling interest of which
         consist of any one or more Principals and/or such other persons
         referred to in the immediately preceding clause (1).

Notwithstanding the foregoing, a Change in Control shall not be deemed to occur
solely because any Person (the "Subject Person") acquired Beneficial Ownership
of more than the permitted amount of the then outstanding Voting Securities as a
result of the acquisition of Voting Securities by the Company which, by reducing
the number of Voting Securities then outstanding, increases the proportional
number of shares Beneficially Owned by the Subject Person, provided that if a
Change in Control would occur


                                       7
<PAGE>

(but for the operation of this sentence) as a result of the acquisition of
Voting Securities by the Company, and after such share acquisition by the
Company, the Subject Person becomes the Beneficial Owner of any additional
voting Securities which increases the percentage of the then outstanding Voting
Securities Beneficially Owned by the Subject Person, then a Change in Control
shall occur.

                  (b)      Severance Amount. Employee shall receive as severance
benefits under this Section 13 three (3) times the highest salary level in
effect for Employee at any time during the Term of the Agreement. Employee shall
also receive a cash amount equivalent of three (3) years of fringe benefits as
described in Section 3(a)(3) in effect as of the Termination Date. Employee
shall also be entitled to receive reasonable attorney's fees and costs incurred
in making a successful claim for compensation and benefits hereunder, including
all costs of arbitration, mediation, or litigation, if necessary.

                  (c)      Schedule of Payments. The Company will make cash
payments due under this Section 14 in the manner described below following
Employee's termination of employment. All other amounts and allowances will be
provided or promptly paid upon submission of receipts or other evidence of
expenses eligible for reimbursement.

                           (1)      All cash and benefits will be paid over
thirty-six (36) months, beginning on the first day of the month following
termination of employment.

                           (2)      In the event of the death of Employee prior
to the payment of all cash due hereunder, all remaining payments may, at the
Company's sole discretion either continue to be paid in accordance with Section
13(c) or be made in a single sum to the Employee's surviving spouse. If Employee
is not married at the time of death, such cash payments may be made to
Employee's estate.

         14.      Disability of Employee.

                  (a)      In the event Employee becomes disabled during the
term of this Agreement, the Company will continue to pay the Employee according
to the compensation provisions of this Agreement during the period of his
disability, until such time as Employee's long term disability insurance
benefits become available. However, in the event Employee is disabled for more
than six (6) continuous months, the Company may terminate Employee's employment.
In this case, the compensation provided for under this Agreement will cease,
except for earned but unpaid Salary and Incentive Compensation Awards and other
benefits and unreimbursed expenses that would be payable on a pro-rated basis
for the fiscal year in which the disability occurred.

                  (b)      During the period the Employee is disabled but is
receiving payments of regular compensation described in this Agreement and as
long as he is physically and mentally able to do so, the Employee will furnish
information and assistance to the Company and from time to time will make
himself reasonably available to the Company to undertake assignments consistent
with his prior position with the Company and his physical and mental health. If
the Company fails to make a payment or provide a benefit required as part of the
Agreement, the Employee's obligation to furnish information and assistance will
end immediately.

         The term "Disability" shall mean the inability of Employee to perform
the duties of his employment due to physical or emotional incapacity or illness
(including, without limitation, alcohol or chemical dependency), where such
inability has continued or is expected to continue for more than 180 days in any
one (1) year period. In the event of a dispute, the determination of Disability
shall be made


                                       8
<PAGE>

as follows: the Company and the Employee (or his executor or personal
representative, as the case may be) shall each appoint a physician competent in
the field of medicine to which such incapacity or illness relates, and two
physicians so selected shall select a third physician who shall be similarly
competent. The decision of a majority of such physicians as to the Disability of
Employee shall be binding on the parties hereto.

         15.      Assignment.

                  (a)      The rights and benefits of Employee under this
Agreement, other than accrued and unpaid amounts due under Section 3(a) hereof,
are personal to him and shall not be assignable. Discharge of Employee's
undertakings in Section 4(c) hereof shall be an obligation of Employee's
executors, administrators, or other legal representatives or heirs.

                  (b)      This Agreement may not be assigned by the Company
except to an affiliate of the Company, provided, however, that if the Company
shall merge or effect a share exchange with or into, or sell or otherwise
transfer substantially all its assets to, another corporation, the Company may
assign its rights hereunder to that corporation.

         16.      Notices. Any notice or other communications under this
Agreement shall be in writing, signed by the party making same, and shall be
delivered personally or sent by certified or registered mail, postage prepaid,
addressed as follows:

         If to Employee:            R. Dirk Allison
                                    ---------------

         If to the Company:         AHS Management Company, Inc.
                                    Attention: General Counsel
                                    One Burton Hills Blvd. - Suite 250
                                    Nashville, Tennessee 37215

or to such other address as may hereafter be designated by either party hereto.
All such notices shall be deemed given on the date personally delivered or
mailed.

         17.      Governing Law. This Agreement shall be interpreted and
enforced in accordance with the laws of the State of Tennessee, without giving
effect to the choice of law provisions of such State.

         18.      Arbitration and Waiver of Jury Trial. Any dispute among the
parties hereto shall be settled by arbitration in Nashville, Tennessee, in
accordance with the then applicable rules of the Model Employment Arbitration
Procedures of American Arbitration Association and judgment upon the award
rendered may be entered in any court having jurisdiction thereof. The arbitrator
shall award all costs, legal expenses and fees to the successful party. The
Company and Employee each hereby waive any right to trial by jury of any dispute
arising under this Agreement.


                                       9
<PAGE>


         19.      Severability. Whenever possible, each provision of this
Agreement shall be interpreted in such manner as to be effective and valid, but
if any one or more of the provisions contained in this Agreement shall be
invalid, illegal or unenforceable in any respect for any reason, the validity,
legality and enforceability for any such provisions in every other respect and
of the remaining provisions of this Agreement shall not be in any way impaired.

         20.      Modification. No waiver or modification of this Agreement or
of any covenant, condition, or limitation herein contained shall be valid unless
in writing and duly executed by the party to be charged therewith and no
evidence of any waiver or modification shall be offered or received in evidence
of any proceeding, arbitration or litigation between the parties hereunder,
unless such waiver or modification is in writing, duly executed as aforesaid and
the parties further agree that the provisions of this section may not be waived
except as herein set forth.

         21.      Entire Agreement. This Agreement contains the entire agreement
of the parties hereto with respect to the subject matter contained herein. There
are no restrictions, promises, covenants or undertakings, other than those
expressly set forth herein. This Agreement supersedes all prior agreements and
understandings between the parties with respect to such subject matter.


                                       10
<PAGE>


         22.      Employer Policies, Regulations and Guidelines for Employee.
Employer may issue policies, rules, regulations, guidelines, procedures or other
informational material, whether in the form of handbooks, memoranda, or
otherwise, relating to its employees. These materials are general guidelines for
Employee's information and shall not be construed to alter, modify or amend this
Agreement for any purpose whatsoever.

         IN WITNESS WHEREOF, the undersigned have executed this Agreement on the
day and year first above written.


                                    AHS MANAGEMENT COMPANY, INC.


                                    By:    /s/ David T. Vandewater
                                         ------------------------------

                                    Title:   President and CEO
                                         ------------------------------


                                    EMPLOYEE


                                    /s/ R. Dirk Allison
                                    ----------------------------------
                                    R. Dirk Allison


                                       11