EXECUTIVE EMPLOYMENT AGREEMENT
                         ------------------------------

              AGREEMENT,  dated as of 9/1/96,  by and  between  DIANON  Systems,
Inc., a Delaware corporation having offices at 200 Watson Boulevard,  Stratford,
Connecticut 06497 (the "Company"),  and James B. Amberson, whose residence is 18
Tubbs Spring Court, Weston, Connecticut 06883 (the "Executive").

              The  Company's  Board of Directors  (the  "Board")  considers  the
continued  services of key  executives of the Company to be in the best interest
of the Company and its stockholders.

              The  Board  desires  to  assure,  and  has  determined  that it is
appropriate  and in the best  interests of the Company and its  stockholders  to
reinforce  and  encourage,   the  continued  attention  and  dedication  of  key
executives  of the  Company to their  duties  without  personal  distraction  or
conflict of interest in circumstances arising from the possibility or occurrence
of a change in control of the Company.

              In  consideration of the premises and the covenants and agreements
contained herein, and other good and valuable consideration, the Company and the
Executive agree as follows:

         1. Services During Certain  Events.  In the event a proposal is made to
effect a Change in Control  (as  defined in  Section 3  hereof),  the  Executive
agrees  that he will not  voluntarily  leave the employ of the  Company and will
render the services  contemplated  in the recitals of this Agreement  until such
proposal for a Change in Control is terminated or abandoned or until a Change in
Control has occurred, except as otherwise provided in Section 2 hereof.

         2. Termination.  For purposes of this Agreement,  a "Termination" shall
be deemed to have occurred in the event that the  Executive's  employment by the
Company is  terminated  at any time from 90 days prior to a Change in Control to
two years following a Change in Control:

              (a) by the Company for reasons  other than  "cause" (as defined in
Section 6 hereof),  "disability"  (as  defined  in  Section 6 hereof),  death or
attainment of age 65;

              (b)  by  the  Executive  following  the  occurrence  of any of the
following events without the Executive's consent:

                    (i) the  assignment  of   the  Executive  to  any  duties or
         responsibilities  that  are  inconsistent  with his  position,  duties,
         responsibilities  or  status  immediately   preceding  such  Change  in
         Control, or a change in his reporting responsibilities or titles within
         the  Company in effect at such time  resulting  in a  reduction  of his
         responsibilities or position at the Company;

                   (ii) a reduction of the Executive's annual salary;

                  (iii) a  material  reduction  in  any  year of  the  ratio  of
         incentive  compensation  or fringe  benefits  received by the Executive
         pursuant to any bonus,  incentive or fringe  benefit plan (the "Benefit
         Plan") to his annual  salary in such year,  which  reduction is greater
         than the average  reduction in the ratio of such incentive compensation


         or fringe benefits to annual salary received by all participants  under
         the Benefits Plans;

                   (iv) a material  increase  in the  amount of travel  normally
         required of the  Executive in  connection  with his  employment  by the
         Company,  or the transfer of the  Executive  to a location  requiring a
         change in his residence; or

                    (v) any  failure by the  Company to comply with an d satisfy
         Section 8 of this Agreement; or

              (c) by the Executive,  if he determines,  in his sole  discretion,
during the 60-day period commencing 180 days following a Change in Control, that
due to the Change in Control he can no longer  effectively  perform  his duties.
For purposes of this Agreement,  any determination by the Executive  pursuant to
the preceding sentence shall be conclusive.

         3. Change in Control.  For  purposes  of this  Agreement,  a "Change in
Control" of the Company shall be deemed to have occurred if:

              (a) individuals who, as of the date hereof,  constitute the entire
Board of  Directors  of the Company (the  "Incumbent  Directors")  cease for any
reason to constitute at least a majority of the Board,  provided,  however, that
any  individual  becoming a director  subsequent  to the date of this  Agreement
whose election,  or nomination for election by the Company's  shareholders,  was
approved  by a vote of at  least a  majority  of the then  In-cumbent  Directors
(other than an election or  nomination  of an  individual  whose  assumption  of
office is the result of an actual or threatened election contest relating to the
election  of  directors  of the  Company,  as such terms are used in Rule 14a-11
under the  Securities  Exchange Act of 1934, as amended (the  "Exchange  Act")),
shall be, for purposes of this  Agreement,  considered as though such individual
were an Incumbent Director; or

              (b)  the  shareholders  of  the  Company  shall  approve  (i)  any
consolidation  or  recapitalization  of the Company (or, if the capital stock of
the Company is affected,  any subsidiary of the Company) or any sale,  lease, or
other transfer (in one transaction or a series of  transactions  contemplated or
arranged  by any  party as a single  plan)  of all or  substantially  all of the
assets of the Company (each of the foregoing being an "Acquisition Transaction")
where (x) the shareholders of the Company  immediately prior to such Acquisition
Transaction   would  not   immediately   after  such   Acquisition   Transaction
beneficially own, directly or indirectly,  shares  representing in the aggregate
more  than  65% of (A) the then  outstanding  common  stock  of the  corporation
surviving or resulting from such merger,  consolidation or  recapitalization  or
acquiring  such  assets  of the  Company,  as the  case  may be (the  "Surviving
Corporation")  (or of its  ultimate  parent  corporation,  if  any)  and (B) the
Combined  Voting  Power  (as  defined  below)  of the  then  outstanding  Voting
Securities (as defined below) of the Surviving  Corporation  (or of its ultimate
parent  corporation,  if any) or (y) the Incumbent  Directors at the time of the
initial approval of such  Acquisition  Transaction  would not immediately  after
such Acquisition  Transaction constitute a majority of the Board of Directors of
the Surviving  Corporation  (or of its ultimate parent  corporation,  if any) or
(ii) any plan or proposal for the liquidation or dissolution of the Company; or

              (c) any Person (as  defined  below)  shall  become the  beneficial
owner (as defined in Rules 13d-3 and 13d-5 under the Exchange Act),  directly or
indirectly,  of securities of the Company  representing  in the aggregate 30% or
more of either  (i) the then  outstanding  shares of the  Company  Common  Stock


("Common  Stock"),  or (ii) the Combined  Voting  Power of all then  outstanding
Voting Securities of the Company;  provided,  however,  that notwithstanding the
foregoing,  a Change  in  Control  of the  Company  shall  not be deemed to have
occurred for purposes of this subsection (c) solely as the result of:

                   (i) the  acquisition of securities by the Company  which,  by
         reducing  the  number  of  shares  of  Common  Stock  or  other  Voting
         Securities  outstanding,  increases  (i) the  proportionate  number  of
         shares of Common Stock  beneficially owned by any Person to 30% or more
         of  the  shares  of  Common   Stock  then   outstanding   or  (ii)  the
         proportionate   voting  power  represented  by  the  Voting  Securities
         beneficially  owned by any Person to 30% or more of the Combined Voting
         Power of all then outstanding Voting Securities; or

                  (ii) an  acquisition of securities if the Incumbent  Directors
         at the time of the  initial  approval  of such  acquisition  would  not
         immediately  after  (or  otherwise  as a result  of)  such  acquisition
         constitute a majority of the Board;

                        (A) any  conversion  of a security that was not acquired
              directly from the Company; or

                        (B)  any  acquisition  of  securities  if the  Incumbent
              Directors at the time of the initial  approval of such acquisition
              would not  immediately  after (or  otherwise  as a result of) such
              acquisition constitute a majority of the Board;

provided,  however, that if any Person referred to in subsections (i) or (ii) of
this clause (c) shall  thereafter  become the beneficial owner of any additional
shares of the Company  Common  Stock or other Voting  Securities  of the Company
(other than pursuant to a stock split, stock dividend or similar  transaction or
an  acquisition  exempt under such  subsection  (ii)),  then a Change in Control
shall be deemed to have occurred for purposes of this clause(c).

              (d)  Notwithstanding  anything  contained in this Agreement to the
contrary,  if the  Executive  experiences  a  Termination  prior to a Change  in
Control and the Executive reasonably  demonstrates that such Termination (A) was
at the request of a Third Party (as defined below) or (B) otherwise  occurred in
connection with or in anticipation of a Change in Control, then for all purposes
of the  Agreement,  the  date of such  Change  in  Control  shall  mean the date
immediately prior to the date of such Termination.

              For purposes of this Agreement:

              "Person" shall mean any  individual,  entity  (including,  without
limitation, any corporation,  partnership,  trust, joint venture, association or
governmental  body and any successor to any such entity) or group (as defined in
Sections  13(d)(3) or 14(d)(2) of the Exchange Act and the rules and regulations
thereunder); provided, however, that Person shall not include the Executive, the
Company, any of its majority-owned  subsidiaries,  any executive benefit plan of
the Company or any of its  majority-owned  subsidiaries or any entity organized,
appointed  or  established  by  the  Executive,   the  Company  or  any  of  its
majority-owned  subsidiaries  for or pursuant to the terms of any such plan,  or
any of their affiliates;


              "Voting  Securities"  shall mean all  securities  of a corporation
having the right  under  ordinary  circumstances  to vote in an  election of the
board of directors of such corporation;

              "Combined Voting Power" shall mean the aggregate votes entitled to
be case  generally in the election of directors of a  corporation  by holders of
then outstanding Voting Securities of such corporation; and

              "Third  Person"  shall  mean a third  party who has  indicated  an
intention, or taken steps reasonably calculated, to effect a Change in Control.

         4. Rights and Benefits upon Termination or Change in Control.

              (a) Severance  Payment.  Subject to Section 6 and 11(a) hereof, in
the event of a Termination the Company shall pay the Executive,  in twelve equal
monthly  installments  beginning no later than 30 days following the Executive's
Termination,  (i) the  greater  of the  Executive's  annual  salary as in effect
immediately prior to (x) the Termination or (y) a Change in Control plus (ii) if
a Change of Control  could have been  deemed to occur as a result of meeting the
conditions  set forth in paragraph 3(a) hereof  (whether or not such  conditions
were the sole reason for a Change of Control), the most recent annual bonus paid
the Executive.  In the event of the  Executive's  death,  such payments shall be
made to Executive's estate or other legal representative.

              (b) Stock Options.  Immediately prior to a Change in Control,  all
outstanding  options  to buy  Company  stock held by the  Executive,  other than
options granted  pursuant to the Company's  Employee Stock Purchase Plan,  shall
become fully vested and immediately exercisable.

              (c) Restricted  Stock.  Immediately  prior to a Change in Control,
any (i) repurchase  agreement or (ii) right of first refusal  agreement  between
the Executive and the Company with respect to the Company stock shall  terminate
and the Executive's ownership of all shares of Company stock shall fully vest.

         5.  Certain  Additional  Payments  by the  Company.  Anything  in  this
Agreement to the contrary  notwithstanding,  in the event it shall be determined
that any  payment,  distribution  or other  action by the  Company to or for the
benefit of the  Executive,  whether  pursuant to the terms of this  Agreement or
otherwise (a  "Payment"),  would be subject to the excise tax imposed by Section
4999 of the Internal  Revenue Code or any interest or penalties  with respect to
such excise tax (such excise tax, together with any such interest and penalties,
are  hereinafter  collectively  referred  to as  the  "Excise  Tax"),  then  the
Executive,  if such Executive has been employed by the Company for five years or
more,  shall be entitled to receive from the Company at the time such Excise Tax
is due an  additional  payment (a "Gross-Up  Payment") in any amount  reasonably
calculated by the Company's  independent auditors such that after payment by the
Executive of all taxes (including any interest or penalties imposed with respect
to such taxes), including any Excise Tax, imposed upon the Gross-Up Payment, the
Executive  retains  an amount of the  Gross-Up  Payment  equal to the Excise Tax
imposed upon the Payments.

         6.  Conditions  to the  Obligations  of the  Company.  The  rights  and
benefits  provided in Section 4 hereof shall not accrue to the  Executive if any
of the following events shall occur:


              (a) The Company shall  terminate the  Executive's  employment  for
"cause." For purposes of this  Agreement,  termination of employment for "cause"
shall mean (i) the Executive's  conviction for, or plea of nolo contendere to, a
felony, (ii) the Executive's engaging in fraud,  misappropriation,  embezzlement
or other act or acts of  dishonesty  resulting  in, or  intended  to result  in,
substantial  personal  enrichment of the Executive at the expense of the Company
or (iii) the Executive's  intentional  and continual  failure  substantially  to
perform  his duties with the Company  (other than a failure  resulting  from the
Executive's  incapacity  due to physical or mental  illness)  which  failure has
continued for a period of at least 30 days after a written  notice of demand for
substantial  performance  has been  delivered  to the  Executive  specifying  in
reasonable  detail the manner in which the Executive has failed to substantially
perform.  Notwithstanding  the foregoing,  the Executive  shall not be deemed to
have been  terminated for cause unless and until there shall have been delivered
to the Executive a copy of a resolution  (x) duly adopted by  three-quarters  of
the  entire  membership  of the  Board,  at a meeting  called  and held for such
purpose  after  reasonable  notice  to  Executive  and an  opportunity  for  the
Executive,  together with the Executive's counsel, to be heard before the Board,
and (y)  finding  that in the good faith  opinion of the  Board,  Executive  was
guilty of  conduct  described  in the  preceding  sentence  and  specifying  the
particulars of such conduct in detail.

              (b)  Following  a  Termination,  the  Executive  shall  not,  upon
receiving a written request to do so, resign as a director and/or officer of the
Company and of each  subsidiary and affiliate of the Company of which he is then
serving as a director and/or officer.

              (c) The Company shall  terminate the  Executive's  employment  for
"disability." For purposes of this Agreement, "disability" shall mean a physical
or psychological  condition of the Executive which renders him unable to perform
his duties for the Company for a period for six months or longer,  as  confirmed
in writing by the Executive's independent physician.

         7. Arbitration and Expenses.

              (a) Any dispute or controversy arising under or in connection with
this  Agreement  shall be settled by  arbitration,  conducted  before a panel of
three arbitrators in Stamford,  Connecticut, in accordance with the rules of the
American  Arbitration  Association  then in  effect.  The  arbitrators  shall be
approved by both the  Company  and the  Executive  and their  decision  shall be
binding on the parties and conclusive for all purposes.  Judgment may be entered
on the arbitrators' award in any court having jurisdiction.  The expense of such
arbitration shall be borne by the Company.

              (b) The Company shall pay or reimburse the Executive for all costs
and  expenses  (including,  without  limitation,   reasonable  attorneys'  fees)
incurred  by the  Executive  as a result  of any  claim,  action  or  proceeding
(including,  without limitation,  a claim, action or proceeding by the Executive
against the Company)  arising out of, or challenging the validity,  advisability
or enforceability of, this Agreement or any provision hereof.

         8. Successors.  The Company shall require any successor (whether direct
or  indirect,  by  purchase,  merger,  consolidation  or  otherwise)  to  all or
substantially all of the business or assets of the Company, by agreement in form
and  substance  satisfactory  to  the  Executive,   expressly,   absolutely  and


unconditionally to assume and agree to perform this Agreement in the same manner
and to the same extent  that the  Company  would be required to perform it if no
such succession had taken place. As used herein, "the Company" shall include any
successor to all or substantially all of the Company's  business or assets which
executes  and  delivers an  agreement  provided  for in this  Section 8 or which
otherwise  becomes bound by all the terms and  provisions  of this  Agreement by
operation of law.

         9. Notice of Termination. Any termination of the Executive's employment
by the Company shall be  communicated  to the Executive at the address set forth
above (or such other address as the Executive shall have notified the Company in
writing for  purposes of this  Agreement)  in a written  notice and,  except for
termination for "cause," shall specify a termination date no sooner than 15 days
after the giving of such notice.

         10. Term of  Agreement.  This  Agreement  shall  terminate on the fifth
anniversary of the date hereof;  provided,  however,  that this Agreement  shall
automatically  renew for successive one-year terms unless the Company's Board of
Directors  notifies  the  Executive  in  writing  at least  30 days  prior to an
expiration  date that it does not wish to renew the  Agreement for an additional
term; and provided further that if a Change in Control occurs during the term of
an additional term of this Agreement, the Agreement shall continue in effect for
two years following such Change in Control.

         11. Miscellaneous.

              (a) Duty to Mitigate:  Other Severance Payments.  If a Termination
is deemed to occur, the Executive shall during the one-year period subsequent to
his  Termination  notify the Company of any employment  when  obtained,  and the
severance  payment  provided  under  Section  4(a) hereof shall be offset by any
compensation,  which he receives from such employment during the one-year period
subsequent to this  Termination.  Furthermore,  the severance  payment  provided
under  Section 4(a) hereof shall also be offset by any other  severance  payment
which the Executive  receives under any  employment  agreement with the Company,
including damages for breach of any such agreement.

              (b) Assignment.  No right,  benefit or interest hereunder shall be
subject to assignment,  anticipation,  alienation,  sale,  encumbrance,  charge,
pledge, hypothecation or set-off in respect of any claim, debt or obligation, or
to execution,  attachment,  levy or similar process; provided, however, that the
Executive may assign any right, benefit or interest hereunder if such assignment
is  permitted  under the terms of any plan or policy  of  insurance  or  annuity
contract governing such right, benefit or interest.

              (c) Construction of Agreement.  Nothing in this Agreement shall be
construed  to amend any  provision  of any plan or policy of the  Company.  This
Agreement is not, and nothing herein shall be deemed to create,  a commitment of
continued employment of the Executive by the Company.

              (d)  Amendment.  This  agreement  may not be amended,  modified or
canceled except by written agreement of the parties.

              (e) Waiver. No provision of this Agreement may be waived except by
a writing signed by the party to be bound thereby.

              (f)  Severability.  In the event that any  provision or portion of
this  Agreement  shall be  determined  to be  invalid or  unenforceable  for any
reason,  the remaining  provisions of this Agreement  shall remain in full force
and effect to the fullest extent permitted by law.


              (g) Taxes.  Any payment or delivery  required under this Agreement
shall be subject to all  requirements  of the law with regard to  withholding of
taxes,  filing,  making of reports and the like,  and the Company  shall use its
best efforts to satisfy promptly all such requirements.

              (h) Governing Law. This Agreement  shall be governed and construed
in accordance with the laws of the State of New York.

              (i)  Entire  Agreement.  This  Agreement  sets  forth  the  entire
agreement and  understanding  of the parties  hereto with respect to the matters
covered hereby.

                                            DIANON SYSTEMS, INC.


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


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