FIRST AMENDMENT TO MASTER SERVICES AGREEMENT


This First Amendment (this  "Amendment") to the Master Service Agreement is made
and entered  into as of the 4th day of December,  1997,  by and among Aetna U.S.
Healthcare  Inc.,  on  behalf  of itself  and all of its  applicable  affiliates
("Aetna USHC")(other than Human Affairs International,  Incorporated ("HAI") and
its subsidiaries), Magellan Health Services, Inc. ("Magellan") and HAI.

                                   WITNESSETH:

WHEREAS,  Aetna  USHC,  Magellan  and HAI have  entered  into a  Master  Service
Agreement dated as of August 5, 1997 (the "Agreement"); and

WHEREAS,  Aetna  USHC,  Magellan  and HAI desire to amend the  Agreement  in the
manner set forth in this Amendment;

NOW, THEREFORE, in consideration of the premises and for other good and valuable
consideration,  the receipt and adequacy of which are hereby  acknowledged,  the
parties hereby agree as follows:

1.  Amendment to Subsection 7.B(ii) of the Agreement.

Subsection  7.B(ii) of the Agreement is hereby amended to read, in its entirety,
as follows:

(ii) "Base  Members"  shall mean (a) with  respect  to  Tranche 1  Members,  the
     Tranche 1 Members as of September  30, 1997 and (b) with respect to Tranche
     2  Members,  the  Tranche 2 Members as of  September  30,  1997;  provided,
     however,  that with respect to Members whose Plan requires the selection of
     primary care physicians but who have not done so ("1111 Members"), all 1111
     Members in a Plan being  serviced by  Contractor  as of September 30, 1997,
     except for 1111 Members in a Plan written on the U.S.  Healthcare  platform
     in  Georgia,  will be included as Base  Members  with  respect to Tranche 1
     Members or Tranche 2 Members,  as  applicable,  and all other 1111  Members
     will not be  included  as Base  Members  with  respect to either  Tranche 1
     Members  or  Tranche 2  Members.

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2.   Amendment to Subsections 7.B(xi) and (xii) of the Agreement.

Subsections  7.B(xi) and (xii) of the Agreement  are hereby  amended to read, in
their entirety, as follows:

(xi) Tranche 1 Members" shall mean Members for whom Contractor provides services
in any of the  following  categories  of products or services:  Managed  Choice,
Managed Behavioral Health, and HMO (including conversions of individuals who are
serviced only in the category  referred to by  Contractor  as "Network"  Members
into Managed Choice,  Managed Behavioral Health, and HMO Members,  and including
conversions  of FPR, CHA or CHI Members (who were not FPR, CHA or CHI Members as
of the Effective Date) into Managed  Choice,  Managed  Behavioral  Health or HMO
Members,  but not conversions of individuals who were FPR, CHA or CHI Members as
of the Effective Date into such categories).  Notwithstanding the foregoing, the
first two hundred fifty thousand (250,000)  individuals who were FPR, CHA or CHI
Members  as of the  Effective  Date  who  convert  to  Managed  Choice,  Managed
Behavioral  Health or HMO  Members  shall be counted  as  Tranche 1 Members  but
discounted at the rate of 75% for the first  Contract Year of this Agreement and
50%  thereafter  (so that each such  Member  is  deemed as only  one-quarter  or
one-half  Tranche 1 Member,  respectively).  After the first two  hundred  fifty
thousand  (250,000)  such  conversions  from FPR,  CHA or CHI Members to Managed
Choice,  Managed Behavioral Health or HMO Members,  no further  conversions from
individuals who were FPR, CHA or CHI Members as of the Effective Date to Managed
Choice,  Managed Behavioral Health or HMO Members shall be included or deemed as
Tranche 1 Members. In the event the names of any of the above service or product
categories  included  in  Tranche  1  Members  are  changed  or any of the above
services or  products  included  in Tranche 1 Members  are  amended,  changed or
subdivided,  the Member for whom  Contractor  provides such changed,  amended or
subdivided  service or product  shall  continue to be a Tranche 1 Member if such
Member would have otherwise  continued to be a Tranche 1 Member  notwithstanding
the change, amendment or subdivision of such product or service.

(xii)  "Tranche  2 Members"  shall mean  Members  for whom  Contractor  provides
products  or  services  in  the  category  of  HMO  (including   conversions  of
individuals  who are serviced only in the category  referred to by Contractor as
"Network" Members and including  conversions of FPR, CHA, CHI, Managed Choice or
Managed Behavioral Health Members (who were not FPR, CHA, CHI, Managed Choice or
Managed  Behavioral  Health Members as of the Effective  Date) into HMO Members,
but not  conversions  of  individuals  who were FPR ,  Managed  Choice,  Managed
Behavioral  Health,  CHA or  CHI  Members  as of the  Effective  Date  into  HMO
Members).  Notwithstanding  the  foregoing,  the first one million  five hundred
thousand  (1,500,000)  individuals  who were FPR,  CHA or CHI  Members as of the
Effective Date and who

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convert to HMO Members  shall be counted as Tranche 2 Members but  discounted at
the rate of 50% (so that each such Member is deemed as only  one-half  Tranche 2
Member).  Upon the first one million  five  hundred  thousand  (1,500,000)  such
conversions from FPR, CHA or CHI Members to HMO Members,  no further conversions
from  individuals  who were FPR, CHA or CHI Members as of the Effective  Date to
HMO Members  shall be included or deemed as Tranche 2 Members.  In the event the
names of any of the above  service or product  categories  included in Tranche 2
Members are changed or any of the above services or products included in Tranche
2 Members are amended,  changed or subdivided,  the Members for whom  Contractor
provides such changed, amended or subdivided services or products shall continue
to be a Tranche 2 Member if such Member would have  otherwise  continued to be a
Tranche 2 Member  notwithstanding  the change,  amendment or subdivision of such
product or service

3. Amendment to Subsection 7.B of the Agreement.
Subsection 7.B is hereby amended by adding new  Subsections  7.B(xiii) and (xiv)
as follows:

(xiii) "CHA" shall mean the  provision to Members of one or more of the products
     or services  described  in Schedule F-1 hereto,  regardless  of the name of
     such product or service and  regardless of the identity of the affiliate of
     Contractor offering or providing such product or service.

(xiv)"CHI" shall mean the  provision  to Members of one or more of the  products
     or services  described  in Schedule F-1 hereto,  regardless  of the name of
     such product or service and  regardless of the identity of the affiliate of
     Contractor offering or providing such product or service.

4. Amendment to Subsection 7.E of the Agreement.

The second  sentence of  Subsection  7.E of the  Agreement is hereby  amended to
read, in its entirety, as follows:

During the  60-day  period  following  expiration  of each  Contract  Year,  the
Operating  Committee  shall  endeavor to agree upon and submit to Aetna USHC and
Contractor a proposed Tranche 1 Statement and Tranche 2 Statement.

5. Amendment to Subsection 7.G of the Agreement.

Subsection 7.G of the Agreement is hereby  amended to read, in its entirety,  as
follows:


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     G.   Except pursuant to Section 7.H of this  Agreement,  from the Effective
          Date until the end of Contract Year ending 2002, Aetna USHC agrees not
          to utilize any vendor for  servicing  of any FPR  Members  serviced by
          Contractor  (other than any FPR Members  covered by Plans  acquired by
          Aetna  USHC or one of its  affiliates  through  purchase  of stocks or
          assets, or merger, consolidation or joint venture with another entity,
          or any other similar  transaction).  Except pursuant to Section 7.H of
          this Agreement,  from the Effective Date until the end of the Contract
          Year  ending  2002,  Aetna USHC  agrees not to utilize  any  vendorfor
          servicing  HMO Members or Managed  Choice  Members  until such time as
          Contractor  (including any of its  Affiliates) has been paid the first
          two and  one-half  million New Members  (as defined  below)  under the
          applicable  Vendor  Contracts.   Notwithstanding  the  foregoing,  the
          Parties  agree that this Section G shall not prohibit  Aetna USHC from
          having  any Member (as  defined  in  Section  19.B of this  Agreement)
          serviced by any vendor  pursuant  to any  provider  arrangements  with
          integrated delivery systems or any existing contractual  commitment of
          Aetna USHC as of the Effective Date. "New Member" shall mean as of any
          relevant  date of  determination,  the sum of (i)  the  number  of HMO
          Members  as of such  date of  determination  minus  the  number of HMO
          Members as of  September  30,  1997 (as  determined  under  Subsection
          7B(ii), as amended),  whether positive or negative and (ii) the number
          of Managed Choice Members as of such date of  determination  minus the
          number  of  Managed  Choice  Members  as of  September  30,  1997  (as
          determined under Subsection 7.B(ii), as amended),  whether positive or
          negative.  Notwithstanding  the  foregoing,  (a) each FPR,  CHA or CHI
          Member as of  September  30,  1997 who  converts  to a HMO or  Managed
          Choice  Member  shall be  discounted  at the rate of 55% (so that each
          such  Member  is deemed as only 45% of one New  Member),  (b)  Managed
          Behavioral  Health  Members as of September  30, 1997 who convert into
          HMO or Managed  Choice  Members  shall not be counted as "New Members"
          and (c) each FPR, Managed  Behavioral  Health,  CHA or CHI Member (who
          was not a FPR,  Managed  Behavioral  Health,  CHA or CHI  Member as of
          September  30,  1997) who converts to a HMO or Managed  Choice  Member
          shall be counted as a New  Member.  This  Section G shall not apply to
          any market in which Contractor is unable to serve Members (whether due
          to  contractual,  licensure,  legal or regulatory  restrictions or any
          other  reason).  Promptly  following  the  expiration of each Contract
          Year,  Aetna USHC will provide  Contractor with a statement  detailing
          the number of New  Members  as of the end of such  Contract  Year.  In
          addition,  when and if Aetna USHC knows that it has achieved 2,500,000
          New  Members  (as  described  herein),   Aetna  USHC  will  so  inform
          Contractor.  During the exclusivity period described above, Aetna USHC
          agrees to use  commercially  reasonable  best efforts to encourage its
          customers to be served by  Contractor  for Managed  Behavioral  Health
          services.



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6. Amendment to Subsection 7.H of the Agreement.

Subsection 7.H of the Agreement is hereby  amended to read, in its entirety,  as
follows:

H.   Acquisitions/Right of First Offer

     (i)  For purposes of this  Subsection H, the following terms shall have the
          following meanings:

          a.   Acquired Healthcare Entity means the acquisition by Aetna USHC of
               all or any  portion of an HMO,  health  insurer or other  managed
               care entity offering health care benefits.

          b.   Behavioral  Healthcare Business means an entity which is engaged,
               in whole or in part, in the provision or management of Behavioral
               Healthcare Services, including the ownership, leasing, operation,
               administration  or management  of an entity or facility  which is
               engaged,  in whole or in part,  in the provision or management of
               Behavioral Healthcare Services.

          c.   Behavioral  Healthcare  Services  means the  provision  of mental
               health  and  substance  abuse  utilization  management,   network
               management,  care management or EAP services for and on behalf of
               an entity or healthcare plan (including self-insured plans) for a
               fee (or other direct or indirect financial benefit).

     (ii) Within  twenty (20) days  following the closing of an  acquisition  by
          Aetna USHC or any of its Affiliates of an Acquired  Healthcare  Entity
          (whether  through  an  acquisition  of  assets  or  stock,  merger  or
          consolidation,  joint venture or other similar  transaction)  (or such
          later  date  as  such  information  may  be  reasonably   obtained  or
          developed), Aetna USHC shall provide Contractor with written notice of
          such  acquisition,  which notice shall state  whether the provision of
          Behavioral   Healthcare   Services  for  the  Plans  of  the  Acquired
          Healthcare  Entity are  performed,  as of the  acquisition  date, by a
          vendor that is not an  affiliate  of the  Acquired  Healthcare  Entity
          (including  by a provider) (a "Third Party  Vendor") or by a component
          of the Acquired  Healthcare Entity itself or a combination thereof (in
          the latter case, the notice shall set forth in reasonable detail which
          categories  of  members  covered by Plans of the  Acquired  Healthcare
          Entity are  serviced  by a Third  Party  Vendor and which  members are
          serviced internally and the number of such members).  If the number of
          members covered by the

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          Plans of the  Acquired  Healthcare  Entity are less than 750,000 as of
          the  acquisition  date or if more than (50%) of the members (as of the
          acquisition  date)  covered  by the Plans of the  Acquired  Healthcare
          Entity which receive provision of Behavioral Healthcare Services do so
          through a Third Party  Vendor,  the  provisions  of Subsection X below
          shall apply; in all other cases,  the provisions of Subsection Y below
          shall apply.

     (iii)The provisions of this  Subsection H shall supersede the provisions of
          Subsection  7.G of this  Agreement with respect to members of Plans of
          an Acquired Healthcare Entity.

          X.   (i)  Within  twenty  (20) days of the  closing  of an  applicable
               acquisition by Aetna USHC or any of its Affiliates of an Acquired
               Healthcare  Entity  (or  such  later  date  as  such  information
               required  in  connection   with  Subsection  (ii)  above  may  be
               reasonably  obtained  or  developed),  Aetna USHC  shall  provide
               Contractor  with  written  notice of its  election  either (a) to
               cause  the  Behavioral  Healthcare  Services  that are  currently
               performed  by  or  for  the  Acquired  Healthcare  Entity  to  be
               performed by Contractor  pursuant to the terms of this  Agreement
               at rates  determined in accordance with the methodology  provided
               for in Section 6 hereof (as if such  services  constituted a "new
               Plan" under subparagraph (a) of Subsection 6.C of this Agreement)
               as further  described in  Subsection  (ii) below (the "Status Quo
               Election"); or (b) to conduct an auction for such services in the
               manner  set  forth  in  Subsections  (iii)  and (iv)  below  (the
               "Auction  Election").  Aetna USHC shall have the option of either
               (x) making a single  Status Quo Election or Auction  Election for
               the  entire  Acquired  Healthcare  Entity or (y)  subject  to the
               proviso below,  making  separate  Status Quo Elections or Auction
               Elections  for  individual  divisions,  units or  legal  entities
               within  the  Acquired  Healthcare  Entity or (z)  subject  to the
               proviso below,  making  separate  Status Quo Elections or Auction
               Elections  for the  individual  Plans of the Acquired  Healthcare
               Entity;  provided,  however, in the event that Aetna USHC intends
               to make separate  elections  under either  subsection  (y) or (z)
               above,  and as a result of such  election  not all members of any
               product  category  (e.g.,  HMO or Managed Choice) of the Acquired
               Healthcare  Entity would be wholly  within  either the Status Quo
               Election or the Auction Election (any such product category shall
               be  referred  to  as a  "Divided  Product  Category"),  then  the
               following  sentence  shall  apply.  With  respect to each Divided
               Product Category (i) Aetna

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               USHC shall have the right to  designate  the number of members to
               be included in the Status Quo Election and (ii) the parties shall
               in good faith mutually agree on the apportionment (based upon the
               number determined in (i)) of the Divided Product Category so that
               the members  included within the Status Quo Election  represent a
               reasonable  cross-section  (considering  factors such as historic
               utilization  rates,  historic  care costs,  historic  revenue per
               member,  contract terms, term and termination  provisions,  among
               other relevant factors) of the Divided Product  Category.  In the
               event the parties do not reach  agreement of the matter  referred
               to within  subsection  (ii) in the preceding  sentence  within 15
               days following delivery of notice of the applicable Election, the
               matter  shall be resolved in  accordance  with Section 13 of this
               Agreement,  provided  that the 60 day period  referred  to in the
               first  sentence of Subsection  13.C shall be 10 business days for
               purposes of this provision.  Notwithstanding the foregoing, Aetna
               USHC  shall not be  obligated  to  exercise  either a Status  Quo
               Election  or an  Auction  Election  with  respect  to  any of the
               activities described in the Excluded Activities Schedule attached
               hereto  (the   "Excluded   Activities").   Consistent   with  the
               Non-Competition  Covenant dated as of December 4,1997, Aetna USHC
               and the Acquired  Healthcare  Entity shall be free to conduct the
               Excluded Activities in any manner they deem appropriate following
               the closing of the acquisition of the Acquired Healthcare Entity.

          (ii) In the event Aetna USHC makes a Status Quo Election,  the parties
               shall cooperate to ensure that the Behavioral Healthcare Services
               are provided by Contractor to the Acquired  Healthcare  Entity as
               soon  as  reasonably   practicable,   consistent   with  existing
               contractual  obligations  of the  Acquired  Healthcare  Entity or
               Aetna USHC and  subject to any  necessary  regulatory  approvals.
               Contractor  may defer  implementation  of the  provision  of such
               services  up to ninety  (90) days from the date of such  election
               notice  if it  has  operational  constraints  on its  ability  to
               perform the Behavioral  Healthcare  Services for the new Acquired
               Healthcare  Entity.  All  members  of Plans for which  Behavioral
               Healthcare  Services  are  performed  as a result of a Status Quo
               Election  shall be  treated  as new  "Members"  for  purposes  of
               Section 7 of this Agreement;  provided, however, it is understood
               that this  provision is not intended to modify the  provisions of
               Section 7, including the annual and aggregate

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               maximum  payment  amounts  set forth  therein  for  Tranche 1 and
               Tranche 2 Payments.

          (iii)Within  thirty  (30) days of the date Aetna USHC makes an Auction
               Election, it shall provide Contractor with an offer (the "Offer")
               of  proposed  rates  for  providing  the  Behavioral   Healthcare
               Services  to all  Members  of  Plans of the  Acquired  Healthcare
               Entity with respect to which the Auction  Election is being made,
               consistent with existing contractual  obligations of the Acquired
               Healthcare  Entity  and  subject  to  any  necessary   regulatory
               approvals.  The offer shall  remain open for a period of not less
               than  thirty  (30) days (the  "Offer  Period").  During the Offer
               Period,  Contractor and its  representatives  and agents shall be
               given reasonable access (subject to a  confidentiality  agreement
               between Aetna USHC and Contractor and subject to compliance  with
               any  confidentiality  obligations  of  Aetna  USHC  or any of its
               Affiliates  with  entities  other  than the  Acquired  Healthcare
               Entity or the seller of the Acquired Healthcare Entity,  provided
               that Aetna  USHC  shall  exercise  commercially  reasonable  best
               efforts   to  obtain  a  waiver   of  any  such   confidentiality
               obligations  for this purpose) to the relevant  books and records
               and  personnel  of the Acquired  Healthcare  Entity to review the
               relevant information on the Behavioral  Healthcare Services.  If,
               prior to the expiration of the Offer Period,  Contractor notifies
               Aetna  USHC in writing  that it desires to accept the Offer,  the
               parties  shall,  as promptly as  practicable,  negotiate  in good
               faith a definitive  agreement for the provision of such services.
               With the exception of the  contingent  payment  provisions  under
               this Section 7 (which shall not pertain) and the rate  provisions
               (which shall reflect the Offer),  the terms and conditions of the
               definitive  agreement  shall  be  substantially  similar  to  the
               existing  applicable Vendor Contract between Contractor and Aetna
               USHC.

          (iv) In the event  the  Offer  Period  expires  for any Offer  without
               Contractor  notifying  Aetna  USHC that it desire to accept  such
               Offer,  Aetna  USHC  shall be free to  solicit  bids  from  third
               parties for the provision of Behavioral  Healthcare  Services for
               Plans of the  Acquired  Healthcare  Entity.  Contractor  shall be
               entitled to participate in the bidding process.  Aetna USHC shall
               otherwise  be  entitled  to operate  the  bidding  process in any
               manner it deems appropriate (including,  without limitation,  the
               ability to conduct

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               separate  auctions  for  individual  divisions,  units  or  legal
               entities with the Acquired  Healthcare  Entity or by Plan type or
               by  geographical  area)  and for such  period of time as it deems
               appropriate. Except as provided below in the penultimate sentence
               of this paragraph,  in the event the terms of Contractor's  final
               bid (if any) are in  aggregate,  better  for Aetna  USHC than all
               other bona fide bids,  then  Aetna  USHC  shall be  obligated  to
               choose  Contractor as the winning bidder,  and the parties shall,
               as promptly as practicable,  negotiate in good faith a definitive
               agreement for the provision of such services.  With the exception
               of the  contingent  payment  provisions  of this Section 7 (which
               shall not pertain) and the term and rate provisions  (which shall
               reflect the  Contractor's  bid),  the terms and conditions to the
               definitive  agreement  shall  be  substantially  similar  to  the
               existing  Vendor Contract  between  Contractor and Aetna USHC. In
               the event the terms of Contractor's final bid (if any) are not in
               aggregate  better  for Aetna  USHC than all other bona fide bids,
               then Aetna  USHC  shall be free to enter into a contract  for the
               provision of such  services  with any bidder on terms that are in
               the aggregate, better for Aetna USHC than Contractor's final bid.
               In the  event  Aetna  USHC  completes  a bona  fide  auction  and
               concludes,  in good faith, that no bidder (including  Contractor)
               has  made a  commercially  reasonable  offer  for  the  services,
               consistent with then current market  conditions,  then Aetna USHC
               may provide  such  services  internally  until such time as it is
               able to obtain a  commercially  reasonable  offer;  provided,  if
               Contractor believes in good faith that it has made a commercially
               reasonable offer for the services  (notwithstanding  Aetna USHC's
               conclusion otherwise),  the matter shall, at Contractor's written
               request,  be  resolved  in  accordance  with  Section  13 of this
               Agreement.  Other than as  required by law,  Contractor  shall be
               prohibited from disclosing to any third parties the terms of this
               subsection H and the fact that it is participating in the bidding
               process.

          (v)  It is  understood  and agreed  that Aetna USHC may not be able to
               cause all  customers  of an Acquired  Healthcare  Entity who have
               elected  Managed  Behavioral  Health  carve-out  services (or who
               elect to  convert  to such  services)  to enter  into a  business
               relationship  with  Contractor.  In the event  Aetna USHC makes a
               Status  Quo  Election  or  Contractor  accepts an Offer or is the
               winning bidder in an Auction Election, Aetna USHC agrees to

                                        9







               make  commercially  reasonable  best  efforts  to  persuade  such
               customers to engage with Contractor.

          (vi) All members of Plans for which Behavioral Healthcare Services are
               performed as a result of an Auction election shall not be treated
               as "Members" for purposes of Section 7 of the Agreement.

     Y.   (i)  Within  seventy-five  (75)  days  following  the  closing  of any
          applicable  acquisition of an Acquired  Healthcare Entity,  Aetna USHC
          shall  take or cause to be  taken,  all  reasonably  necessary  action
          (consistent  with  existing  contractual  obligations  of the Acquired
          Healthcare Entity and subject to any necessary  regulatory  approvals)
          to segregate  (unless already  segregated)  the Behavioral  Healthcare
          Business  operations of the Acquired Healthcare Entity into a separate
          and  distinct   division  or  subsidiary  (as  segregated,   the  "BHB
          Component").  In segregating the BHB Component,  Aetna USHC shall have
          the option (the "Put Option") of notifying  Contractor that it intends
          to (a) discontinue  certain services which were previously provided by
          the Acquired  Healthcare Entity or by Third Party Vendors prior to the
          closing of the acquisition of the Acquired  Healthcare  Entity and (b)
          causing those  services to be performed by Contractor  pursuant to the
          terms of this Agreement at the rates determined in accordance with the
          methodology  provided  for in  Section 6 hereof  (as if such  services
          constituted a "new plan" under  subparagraph  (a) of Subsection 6.C of
          this  Agreement)  as  further  described  in  Subsection  (ii)  below;
          provided,  however, if as a result of such Put Option, not all Members
          of any product  category (e.g., HMO or Managed Choice) of the Acquired
          Healthcare  Entity would be wholly subject to the Put Option (any such
          product   category  shall  be  referred  to  as  a  "Divided   Product
          Category"),  then the following  sentence shall apply. With respect to
          each Divided  Product  Category (i) Aetna USHC shall have the right to
          designate  the number of Members to be  included in the Put Option and
          (ii)  the  parties  shall  in  good  faith   mutually   agree  on  the
          apportionment (based upon the number determined in (i)) of the Divided
          Product  Category so that the Members  included  within the Put Option
          represent a  reasonable  cross-section  (considering  factors  such as
          historic utilization rates,  historic care costs, historic revenue per
          member, contract terms, term and termination  provisions,  among other
          relevant  factors) of the Divided Product  Category.  In the event the
          parties do not reach agreement of the

                                       10







          matter referred to within  subsection  (ii) in the preceding  sentence
          within 15 days  following  delivery of notice of the Put  Option,  the
          matter  shall  be  resolved  in  accordance  with  Section  13 of this
          Agreement,  provided that the 60 days period  referred to in the first
          sentence of Subsection  13.C shall be 10 business days for purposes of
          this provision. Notwithstanding the foregoing, Aetna USHC shall not be
          obligated  to  segregate  (or exercise its Put Option) with respect to
          any of the Excluded  Activities.  Consistent with the  Non-Competition
          Covenant,  Aetna USHC and the Acquired Healthcare Entity shall be free
          to conduct the Excluded Activities in any manner they deem appropriate
          following the closing of the  acquisition  of the Acquired  Healthcare
          Entity.

     (ii) In the event Aetna USHC desires to exercise  its Put Option,  it shall
          provide  Contractor  with written  notice of such intent within twenty
          (20) days  following  the closing of the  acquisition  of the Acquired
          Healthcare Entity, which notice shall specify in reasonable detail the
          services to be performed  by  Contractor,  the Plans  affected and the
          number of members involved. The parties shall then cooperate to ensure
          that the relevant  services are provided by Contractor to the Acquired
          Healthcare Entity as soon as reasonably  practicable,  consistent with
          existing contractual obligations of the Acquired Healthcare Entity and
          subject to any necessary  regulatory  approvals.  Contractor may defer
          implementation  of that provision up to ninety (90) days from the date
          of the  election  notice  if it  has  operational  constraints  on its
          ability to perform the Behavioral Healthcare Services for the Acquired
          Healthcare   Entity.   All  members  of  Plans  for  which  Behavioral
          Healthcare Services are performed as a result of a Put Option shall be
          treated as new "Members" for purposes of Section 7 of this  Agreement;
          provided,  however,  it is  understood  that  this  provision  is  not
          intended to affect the payment  methodology,  including the annual and
          aggregate maximum payment amounts set forth in Section 7 for Tranche 1
          and Tranche 2 Payments.

     (iii)Within  seventy-five (75) days following the closing of an acquisition
          of an Acquired  Healthcare Entity,  Aetna USHC shall prepare (or cause
          to be  prepared) a pro forma income  statement  (the "Pro Forma Income
          Statement")  for the BHB  Component for the twelve month period ending
          on the later of (a) the closing  date of the  acquisition  and (b) the
          month end for which a pro forma

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          income  statement can  reasonably  be prepared..  The Pro Forma Income
          Statement  shall be  prepared on a basis  which  assumes  that the BHB
          Component had operated  separately  over this twelve month period with
          separate contracts on such terms as Aetna USHC would be willing to put
          into place,  including  term and rates for  providing or arranging the
          provision of Behavioral  Healthcare Services to all Members covered by
          Plans of such Entity for the assumed  term (the  "Applicable  Contract
          Rates"),   which  term  and  rates  shall  be  clearly   indicated  as
          assumptions  in the Pro Forma Income  Statement.  The Pro Forma Income
          Statement  shall  include  customary  income  and  expense  categories
          (including  allocations of indirect services and overhead costs, which
          are  intended  to present  the  operations  as if they  operated  on a
          stand-alone  basis),  and including  Earnings Before Interest,  Taxes,
          Depreciation & Amortization ("EBITDA").

     (iv) Within  seventy-five (75) days following the closing of an acquisition
          of an Acquired Healthcare Entity, Aetna USHC shall offer (an "Offer"),
          or cause to be offered,  to  Contractor  the right to purchase the BHB
          Component of the Acquired  Healthcare  Entity. The Offer shall include
          all material  terms of the proposed sale  including the purchase price
          and  Applicable  Contract  Rates.  Each Offer shall  remain open for a
          period of not less than forty-five (45) days (the "Offer Period").

     (v)  During the Offer Period, Contractor and its representatives and agents
          shall  be  entitled  to  conduct  a due  diligence  review  of the BHB
          Component and the Acquired Healthcare Entity, in order to evaluate the
          Offer,   and  shall  be  given   reasonable   access   (subject  to  a
          confidentiality  agreement  between  Contractor  and  Aetna  USHC  and
          subject to compliance  with any  confidentiality  obligations of Aetna
          USHC or any of its  Affiliates  with entities  other than the Acquired
          Healthcare  Entity or the seller of the  Acquired  Healthcare  Entity,
          provided that Aetna USHC shall exercise  commercially  reasonable best
          efforts to obtain a waiver of any such confidentiality obligations for
          this purpose) to the books and records and personnel of the Qualifying
          Entity  and  BHB  Component,   including  the  supporting  information
          utilized  to  prepare  the  Pro  Forma  Income  Statement  of the  BHB
          Component.


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     (vi) If, prior to the expiration of the Offer Period,  Contractor  notifies
          Aetna USHC in writing that it desires to accept the Offer, the parties
          shall,  as  promptly  as  practicable,   negotiate  in  good  faith  a
          definitive  purchase  agreement  (which,  other  than  the  Applicable
          Contract Rates and other economic terms,  shall contain  substantially
          the same terms and  conditions  contained in the  definitive  purchase
          agreement  pursuant to which Magellan  acquired  Contractor from Aetna
          USHC) and a definitive  vendor  contract,  on  substantially  the same
          terms  and  conditions  (other  than  the  rates  which  shall  be the
          Applicable   Contract  Rates)  as  those  contained  in  the  existing
          applicable Vendor Contracts between Contractor and Aetna USHC.

     (vii)In the event that Contractor  notifies (the  "Non-acceptance  Notice")
          Aetna  USHC that it does not  accept  the  Offer or the  Offer  Period
          expires for any Offer without Contractor  notifying Aetna USHC that it
          desires to accept  such Offer,  Aetna USHC shall take,  or cause to be
          taken, all commercially  reasonable  efforts to sell the BHB Component
          to a non-affiliate of Aetna USHC, provided, however, that the purchase
          price,  rates for services and other  material  terms of any sale to a
          non-affiliate  shall not be more  favorable  (viewed  on an  aggregate
          basis) to the third party than the purchase price, Applicable Contract
          Rates  and  other  material  terms  set  forth  in  the  Offer  to the
          Contractor  (viewed on an aggregate  basis).  Magellan  shall have the
          right to submit a bid in connection with any auction conducted to sell
          the BHB  Component.  If Aetna USHC (or its  Affiliate,  as applicable)
          does not enter into a  definitive  agreement  with a third  party with
          respect to the sale of the BHB  Component  by the end of the  "Selling
          Period" (as defined below), then for a period of 45 days following the
          expiration  of the  Selling  Period (the  "Option  Period"),Contractor
          shall have the option (the  "Purchaser  Option")  to purchase  the BHB
          Component on terms equal to the more  favorable to Aetna USHC of (a) a
          purchase  price  equal to the fair market  value of the BHB  Component
          (assuming the  Applicable  Contract  Rates and other material terms of
          the Offer apply), as determined by a mutually  acceptable  independent
          investment  banking  firm or (b) on terms equal to the most  favorable
          terms to Aetna USHC (viewed on an aggregate basis) received during the
          Selling  Period by Aetna  USHC from a bona fide third  party  making a
          bona fide offer (the "Bona fide Offer") to purchase the BHB  Component
          (an offer shall

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          be considered a Bona fide Offer only if, among other things, the third
          party was willing to  consummate  the offer  pursuant to its terms and
          that the information received from Aetna USHC upon which the offer was
          based was true and  correct  in all  material  respects).  During  the
          Option Period,  Contractor and its representatives and agents shall be
          entitled to conduct  confirmatory  due  diligence of the BHB Component
          subject  to a  confidentiality  agreement.  In  the  event  Contractor
          notifies  Aetna USHC in writing  before the  expiration  of the Option
          Period that it desires to exercise its Purchaser  Option,  the parties
          shall negotiate in good faith a definitive  purchase  agreement (which
          shall contain  substantially the same terms and conditions (other than
          with  respect to rates and other  economic  terms) as contained in the
          definitive  purchase  agreement  pursuant to which  Magellan  acquired
          Contractor  from  Aetna  USHC)  and a  vendor  contract  charging  the
          Applicable Contract Rates and for the term specified in the Offer (or,
          in the event  there is a Bone Fide  Offer  that is more  favorable  to
          Aetna USHC than the fair  market  valuation,  at the rates and for the
          term  applicable  to the Bona fide  Offer) and  including  all Members
          covered by any Plan of the Acquired Healthcare Entity. For purposes of
          this Subsection  (vi), the term "Selling Period" shall mean the period
          commencing  upon the  earlier  of the  receipt  of the  Non-acceptance
          Notice or the expiration of the Offer Period (the "Commencement Date")
          and continuing for 120 days following the Commencement Date,  provided
          that the Selling  Period  shall  continue for 150 days  following  the
          Commencement Date if Aetna USHC (or its Affiliate,  as applicable) has
          entered into a letter of intent with a third party with respect to the
          sale of the BHB Component  within 120 days following the  Commencement
          Date.

     (viii) In the event  that  Aetna  USHC (or its  Affiliate,  as  applicable)
          enters into a definitive  agreement during the Selling Period, for any
          BHB  Component,  and  the  purchase  and  sale  contemplated  by  such
          definitive  agreement is not consummated within six months of the date
          such  agreement was executed (or for such longer period as any federal
          or state  regulatory  or antitrust  approvals  may be  pending),  then
          Contractor  shall  have a  Purchase  Option  with  respect to such BHB
          Component  for 45 days  following  the  expiration  of such six  month
          period (or longer) on the same terms as described  above in Subsection
          (vii).

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     (ix) In the event any state or federal  regulatory or  governmental  entity
          prevents  the sale to  Contractor  of the BHB  Component  (or any part
          thereof) or the sale of the BHB Component is not  consummated  because
          the  conditions  to  closing  set  forth  in the  definitive  purchase
          agreement are not satisfied or waived (other than the  nonsatisfaction
          of a condition  as a result of a breach by Aetna USHC of the  purchase
          agreement),  after  reasonable  good  faith  efforts  to  obtain  such
          approvals or satisfy such conditions, then Aetna USHC shall be free to
          dispose  of the  BHB  Component  (or the  relevant  part  thereof)  or
          continue its operations in any manner Aetna USHC deems appropriate.

7. Amendment to Section 12 of the Agreement.

Section 12 is hereby amended by adding a new Subsection 12.C as follows:

C. HAI and Aetna USHC shall each have the right to audit and inspect at any time
during  normal  business  hours  upon  reasonable   notice,   (a)  documents  or
information  pertaining to verification of membership,  in the possession of the
other party,  covered under this Agreement and the Vendor  Contracts and (b) any
documentation or information  relevant to determinations under Subsection 6.C of
this  Agreement,  in each case  subject  to a  confidentiality  agreement  to be
entered into between the parties.

8.    Miscellaneous.

a.   All references in the Agreement to the "Agreement" and any other references
     of similar  import shall  henceforth  mean the Agreement as amended by this
     Amendment.  All  capitalized  terms used but not otherwise  defined  herein
     shall have the meaning ascribed to them in the Agreement as amended by this
     Amendment.

b.   Except to the extent  specifically  amended by this  Amendment,  all of the
     terms and conditions contained in the Agreement shall be and remain in full
     force and effect.

c.   This  Amendment  shall be  binding  upon and inure to the  benefit of Aetna
     USHC, Magellan and HAI and their respective successors and assigns.

d.   In the event of any  inconsistency  or conflict  between this Amendment and
     the Agreement, the terms, provisions and conditions of this Amendment shall
     govern and control.


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e.   This  Amendment  shall be governed by and construed in accordance  with the
     internal laws of the State of Delaware.


IN WITNESS  WHEREOF,  the parties  hereto have executed this Amendment as of the
date first written above.

AETNA U.S. HEALTHCARE INC.             MAGELLAN HEALTH SERVICES, INC.

By:  /s/ Daniel S. Messina             By:  /s/ Craig L. McKnight
     -----------------------               -------------------------------------
     Name: Daniel S. Messina               Name: Craig L. McKnight
     Title: Deputy CFO                     Title: Executive Vice President & CFO
     Date: December 4, 1997                Date: December 4, 1997


                                       HUMAN AFFAIRS INTERNATIONAL,
                                        INCORPORATED


                                       By:  /s/ Thomas M. Bendoratis
                                           -------------------------------------
                                           Name: Thomas M. Bendoraitis
                                           Title: Vice President & CFO
                                           Date: December 4, 1997


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