EMPLOYMENT AGREEMENT


         This AGREEMENT made effective September 1, 1996 between Dianon Systems,
Inc., a Connecticut corporation, and any successor thereto, hereinafter referred
to  as  the  "Company,"  and  James  B.  Amberson,  M.D.,  residing  in  Weston,
Connecticut, hereinafter referred to as "Employee."

                                   WITNESSETH:

         WHEREAS,  the Company  wishes to reinforce the capacity of Employee,  a
senior  management  official of the  Company,  to  implement  the  policies  and
programs  established  by the Company,  and to provide for the protection of the
goodwill,  confidential information, and proprietary rights and interests of the
Company,  in each case on the  terms and  subject  to the  conditions  set forth
below; and

         WHEREAS,  Employee's business contacts and relationships are crucial to
the  financial  and  business  success of the  Company,  and the  services  that
Employee should render hereunder to the Company are unique and valuable; and

         WHEREAS,  the  parties  desire to reduce  the terms and  conditions  of
Employee's employment to writing;


         NOW,  THEREFORE,  in  consideration of the terms and conditions and the
mutual  covenants  contained in this Agreement,  the Company and Employee hereby
agree as follows:

         1.   Employment
              ----------

              The Company  hereby employs  Employee and Employee  hereby accepts
such employment upon the terms and conditions hereinafter set forth. The parties
acknowledge  that  Employee's  employment  with  the  Company  is  at  will  and
terminable by either party at any time for any reason.

         2.   Duties and Responsibilities
              ---------------------------

              Employee shall perform with continuous  diligence those activities
assigned  to  Employee  by  the  Company  including:   active  participation  in
laboratory  and  market  research,  keeping  full and  complete  records  of all
business and/or research  activities in which Employee  engages and surrendering
all such records and materials on request,  improving  strategies  for achieving
the Company's goals,  motivating co-worker  performance,  keeping abreast of all


new  developments  in Employee's  area of expertise,  participating  actively in
research and business meetings, and abiding by all Company policies.

         3.   Term
              ----

              This  Agreement  shall  begin on the  effective  date  hereof  and
continue until terminated under the terms contained herein.

         4.   Salary
              ------

              The Company  shall  compensate  Employee for  Employee's  services
during the term of this  Agreement on a salaried  basis paid bi-weekly at a rate
determined by the Company from time to time.

         5.   Fringe Benefits
              ---------------

              During the term of this Agreement,  Company shall provide Employee
all benefits and emoluments as authorized  for all other  salaried  employees of
the Company as they may be modified from time to time by the Company  during the


term of this  Agreement,  including  health and  medical  insurance,  disability
insurance,  life insurance,  sick leave, vacation,  holidays and retirement plan
participation.

         6.   Termination
              -----------

              a. This   Agreement  shall  terminate  on  any  of  the  following
occurrences:

                  (i)  Employee's death;

                  (ii) Employee's disability for a period of 90 days or more;

                  (iii) mutual  agreement  of  the  parties  reduced  to writing
                        signed by both parties;

                  (iv)  voluntary resignation by Employee;

                  (v)   termination by the Company without Stated Cause;

                  (vi)  termination by the Company with Stated Cause.

              b. Cause shall mean Employee's

                  (i)   gross negligence;

                  (ii)  insubordination;

                  (iii) willful misconduct.

              c. "Stated Cause" shall mean Cause communicated to Employee by the
Company in a Notice of Termination.


              d. "Notice of  Termination"  shall mean  written  notice given  by
either party to the other of an intention to terminate this  Agreement  pursuant
to subparagraphs (a)(iv), (v) or (vi) of this Paragraph of this Agreement.

              e. Notice  of  Termination  shall  be  sent by  certified  mail or
registered mail, return receipt requested,  first class postage prepaid,  to the
residence in the case of Employee,  and to its  principal  office in the City of
Stratford,  Connecticut,  to the  attention of the  President in the case of the
Company.

         7.   Compensation after Termination
              ------------------------------

              (a) The  "Termination  Date"  shall  be the date  Employee  ceases
providing services to the Company as an employee. In the event Employee provides
Notice of Termination to the Company less than four weeks prior to the date such
Notice  identifies  as the  Termination  Date,  then the  date  said  Notice  of
Termination is received by the Company shall be the Termination Date.

              (b) Employee  will not receive any  compensation  from the Company
after the  Termination  Date  other than  accrued,  unused  vacation,  except as
described under  Paragraphs (c) and (d) of this Section 7 of this Agreement,  if


applicable.  Employee's  participation  in all  fringe  benefits  offered by the
Company to its employees will cease  immediately on the Termination  Date except
as  described  in  Paragraph  (c)  of  this  Section  7 of  this  Agreement,  if
applicable. Nothing in this Agreement, however, is intended to impair any rights
vested under law in any benefit plan of the Company.

              (c) If this Agreement and Employee's  employment  with the Company
is  terminated  by the  Company  without  stated  cause,  the  Company  will pay
Employee:

                   (i)  For  a  period  of  six   months   beginning   with  the
                        Termination Date at Employee's current rate of pay as of
                        the day preceding  the  Termination  Date,  less amounts
                        equivalent  to income  Employee  earns  during  said six
                        month  period  from  other   employment  or  independent
                        consulting.

                   (ii) During said six month  period,  Employee  shall act as a
                        consultant  to the Company as  requested  by the Company
                        for up to six days per month.

                   (iii)During  said  six  month   period,   the  Company   will
                        contribute   towards   the   premium   cost  of  medical
                        continuation  coverage  for Employee  and/or  Employee's
                        dependents  on the  same  basis  as it then  contributes
                        towards the medical  coverage of active employees and/or
                        their  dependents,  for any months in said period during
                        which Employee and/or Employee's dependents are eligible
                        and elect to continue such coverage.

                   (iii)During said six month period,  the Company will continue
                        to  provide  Employee  any car  allowance  Employee  was
                        receiving at the time of the Termination Date.


              (d) Employee's  participation  in all incentive  plans,  including
bonus and commission,  stock options, restrictive stock purchase plans and other
incentive  compensation programs will terminate on the Termination Date. If this
Agreement terminates (i) by Employee's voluntary  resignation with at least four
weeks'  notice to the  Company or (ii) by  termination  by the  Company  without
Stated  Cause,  the Company will make its best efforts to allocate on a pro rata
basis  based  upon the  number of days from  January 1 to the  Termination  Date
divided by 365, a portion of each such incentive  award to be paid or awarded to
Employee or his estate at the time  payment or awards under any such program are
made to active  employees for the year or other related time period in which the
Termination Date falls.

         8.   Company Property
              ----------------

              On the  Termination  Date, or at any earlier point in time after a
Notice of  Termination  is  received  when a request is made by the  Company for
same,  Employee  will turn over to the  Company all notes,  reports,  memoranda,
books,  records,   chemicals,   devices  and  documents,   whether  in  written,
typewritten,  computerized or any other form, which are in Employee's possession
or under Employee's control,  whether prepared by Employee or others, related to
the Company or relating to the business of the Company. At the conclusion of the
six month period  described in paragraph (c) of Section 6 of this Agreement,  or


at any  earlier  point in time when a request is made by the  Company  for same,
Employee shall also return to the Company any Company car,  keys,  parking card,
credit card, business cards or other materials related to Employee's  employment
with the Company or the operation of the Company.

         9.   Remedy for Breach
              -----------------

              Employee acknowledges:

                   (a)  that  Employee  may be a  director  and  officer  of the
                        Company and as such Employee  would be conversant  with,
                        and have access to, the business affairs, records, trade
                        secrets,   customers  and  customer  lists,   suppliers,
                        supplier lists, patents, technical know-how,  chemicals,
                        devices,    sales    or    distribution    agents    and
                        representatives,   sales  or  distribution   agents  and
                        representatives'   lists,  and  other  confidential  and
                        proprietary information of the Company;


                   (b)  that  Employee's   compliance  with  the  covenants  and
                        agreements in this Agreement is necessary to protect the
                        goodwill and other proprietary  interest of the Company;
                        and

                   (c)  that a breach of Employee's  covenants and agreements in
                        this Agreement will result in continuing and irreparable
                        damage  to  the  Company  for  which  there  will  be no
                        adequate remedy at law.

              Both the parties  recognize that the services to be rendered under
this  Agreement  by  Employee  are  special  and unique and of an  extraordinary
character,  and that in the event there is a breach by Employee of the terms and
conditions of this Agreement to be performed by Employee, then the Company shall
be entitled,  if it so elects,  to institute  and prosecute  proceedings  in any
court of competent  jurisdiction  either in law or in equity,  to obtain damages
for any breach of this Agreement, or to enforce the specific performance thereof
by Employee.


         10.  Employee Representation
              -----------------------

              Employee  warrants and  represents  that neither the execution and
delivery  nor the  performance  of this  Agreement  by Employee  will in any way
violate, or conflict with, any other agreement by which Employee may be bound or
any duty or obligation  to which  Employee may be subject and that Employee will
take all steps necessary to comply with the representation.

         11.  Proprietary Information
              -----------------------

              Employee  hereby  agrees to all the terms  and  conditions  of the
Company's Employee Proprietary  Information Agreement attached hereto as Exhibit
A and incorporated herein and has executed a copy thereof concurrently with this
Agreement.

         12.  Assignments
              -----------

              The rights and  obligations of Employee under this Agreement shall
be  assignable  to and binding  upon the  successors  and assigns of the Company
including any  corporation  organized by the Company to carry on the business of
the Company.


         13.  Entire Agreement
              ----------------

              This instrument  contains the entire Agreement of the parties.  It
may not be changed orally,  but only by agreement in writing signed by the party
against  whom  enforcement  of any waiver,  change,  modification,  extension or
discharge  is  sought.   This  Agreement   supersedes  any  other  agreement  or
understanding  existing  between  Employee  and  the  Company  relating  to  his
employment or the other matters covered herein.

         14.  Severability
              ------------

              If any provision of this  Agreement  shall be held  invalid,  such
invalidity  shall not affect any other  provisions of this Agreement not held so
invalid,  and only such provisions shall to the full extent  consistent with the
law remain in full force and effect.

         15.  Applicable Law
              --------------

              This  Agreement  shall be  governed  by the  laws of the  State of
Connecticut.


              IN WITNESS  WHEREOF,  the  parties  have  executed or caused to be
executed this Agreement as of the date first above written.


                                            DIANON SYSTEMS INC.




                                             BY: /s/ Richard A. Sandberg
                                                 --------------------------- 




                                             /s/ James B. Amberson
                                             ---------------------------
                                             JAMES B. AMBERSON, M.D.


                                                                     Exhibit A
                                                                     --------- 

                                    AGREEMENT
                                    ---------

         THIS  AGREEMENT  made this 1st day of  September,  1996 by and  between
DIANON  SYSTEMS,  INC.,  its  affiliates,  subsidiaries,  successors and assigns
(collectively called hereinafter  "DIANON") and James B. Amberson, an individual
residing in Weston, Connecticut (hereinafter called "Employee").

         In  consideration  of  Employment  Agreement of this date  Employee and
DIANON acknowledge, represent and agree to the terms and conditions set forth in
this Agreement.

         (1) Employee's  employment  with DIANON creates a relationship of trust
and  confidence  between the parties.  Employee  agrees  that,  during and after
his/her  employment  with DIANON,  Employee  will not use or disclose,  or allow
anyone else to use or disclose,  any  confidential  information  relating to the
products, sales and/or business affairs of DIANON or of any customer or supplier
of DIANON,  or any  information  created,  discovered,  or  developed  by or for
DIANON, or acquired by DIANON,  that has commercial value in DIANON's present or
future business ("Confidential Information"),  except as may be necessary in the
performance  of  Employee's  employment  with DIANON or as may be  authorized in
advance by  appropriate  officials of DIANON.  By way of  illustration,  but not
limitation,   Confidential  Information  includes  processes,   formulas,  data,
know-how, inventions, improvements,  techniques, marketing plans, product plans,
strategies,  forecasts,  customer lists and any other  information  Employee has
reason to know  DIANON  would  like to treat as  confidential  for any  purpose.
Employee  agrees to keep  Confidential  Information  secret  whether  or not any
document containing such information is marked confidential.

         (2) All rights, title and interest in all records, documents, files and
the business of DIANON,  whether or not produced by the  Employee,  shall be and
remain the property of DIANON.  Upon  termination  of  employment,  the Employee
shall not have the right to remove any such records  frorm the office of DIANON.
In  addition,  Employee  agrees  to  promptly  return to  DIANON  all  things of
whatsoever  nature that belongs to DIANON,  and all records (in whatsoever form,
format or medium) containing or related to Confidential Information of DIANON.


         (3) The Employee shall,  while employed by DIANON,  devote his/her best
efforts and his/her full time to the business of DIANON.

         (4) In the event of a breach or threatened  breach of the provisions in
this  Agreement,  DIANON  shall be entitled to an  injunction  restraining  such
breach,  it being  recognized  that any injury  arising  from a breach  would be
irreparable  and would have no adequate  remedy at law; but nothing herein shall
be construed as prohibiting  DIANON from pursuing any other remedy available for
such  breach of  threatened  breach.  In the event  that  Employee  breaches  or
threatens  a breach of this  Agreement,  DIANON  shall be  entitled  to have its
reasonable  legal fees and costs  paid by the  Employee  for any legal  services
relating to the breach or threatened breach.

         (5) This Agreement is not intended,  and should not be construed in any
way, as a contract of  employment  for a definite  period of time or to limit or
restrain   DIANON's  or  the  Employee's   right  to  terminate  the  employment
relationship at any time.

         (6) In the  event any  provision  or  paragraph  of this  Agreement  is
declared  to be invalid or  unenforceable,  then the  balance of this  Agreement
shall remain in full force and effect.

         (7) This Agreement  shall be construed and enforced in accordance  with
the laws of the State of Connecticut.

         (8) The  foregoing  contains the entire  Agreement  between the parties
pertaining to confidential  DIANON  documents and  information.  No modification
thereof shall be binding upon the parties unless the same is in a writing signed
by the  respective  parties.  This Agreement and all of the terms and conditions
contained  herein  shall  remain in full force  during the period of  employment
notwithstanding any change in compensation.


         (9)  Employee   represents  and  warrants  that  he/she  has  no  other
agreements or  commitments  that would hinder or prevent  performance of his/her
job  responsibilities  with DIANON.  Unless authorized to do so, Employee agrees
not to disclose to DIANON or use in his/her employment with DIANON any invention
or  confidential  information  belonging to any former  employer or to any other
person other than DIANON.

         IN WITNESS WHEREOF,  the parties have entered into this Agreement as of
the date set forth above.

 
Employee:                                      DIANON SYSTEMS, INC.


/s/ James B. Amberson                   By:    /s/ Richard A. Sandberg
- ---------------------                          -----------------------


Date:  9/1/96                           Date:  9/1/96
       --------------                          -----------------------