BIO-IMAGING TECHNOLOGIES, INC.

                                 April 15, 1998

Mark L. Weinstein, President & Chief Executive Officer
Bio-Imaging Technologies, Inc.
830 Bear Tavern Road
West Trenton, NJ 08628-1020

Dear Mark:

           On behalf  of the Board of  Directors  of  Bio-Imaging  Technologies,
Inc., the (Company) I am pleased to offer you the following compensation package
in  connection  with  your  employment  as the  Company's  President  and  Chief
Executive Officer.

           a)        BASE  SALARY.  You will be paid an  annual  base  salary of
                     $180,000  payable  in  bi-weekly  installments.  Such  base
                     salary shall be reviewed at the end of each 12-month period
                     of  employment  and any  adjustments  to be made  shall  be
                     determined by the Board of Directors at that time.

           b)        BONUSES.  You will be eligible for and may receive bonuses,
                     the  amount of which are to be  determined  by the Board of
                     Directors in its sole discretion.

           c)        INCENTIVE  COMPENSATION.  You will be  eligible  for awards
                     from the Company's incentive  compensation plans on a basis
                     commensurate with your position and responsibility.

           d)        STOCK OPTIONS. Upon the date hereof, you will be granted an
                     option to purchase up to 150,000  shares of Common Stock of
                     the  Company at a purchase  price equal to 100% of the fair
                     market  value of the Common Stock on the date of the grant,
                     which  options  shall vest as  follows:  50,000 on the date
                     hereof and 25,000 on each of the first,  second,  third and
                     fourth  anniversary  of the date of the  grant.  This stock
                     option grant is in addition to existing stock option grants
                     to you relating to your option to purchase  100,000  shares
                     of Common Stock of the Company.

           e)        RELOCATION  EXPENSES.  You will,  upon  presentation to the
                     Company of receipts therefor,  be reimbursed by the Company
                     for  actual,  out-of-pocket  relocation  expenses,  if any,
                     related to the purchase of a new primary  residence for the
                     purpose of  relocating  closer to the  Company's  principal
                     executive  offices  in  West  Trenton,  New  Jersey.  These
                     expenses   may  include  the   following:   (i)   realtor's
                     commission,  not to  exceed 6%  payable  on the sale of the
                     Employee's  existing primary residence;  (ii) other closing
                     costs, not to exceed $2,000 and (iii) expenses  incurred in
                     moving the  contents of your  existing  primary  residence,
                     provided,  however,  that in no  event,  shall  the  amount
                     payable by the Company  pursuant to this subsection  exceed
                     $50,000.

<PAGE>


           f)        EXPENSES.  Subject to and in accordance  with the Company's
                     policies  and  procedures,  you are  hereby  authorized  to
                     incur, and, upon presentation of itemized  accounts,  shall
                     be  reimbursed  for any and all  reasonable  and  necessary
                     business-related  expenses,  which expenses are incurred by
                     you on behalf of the Company.

           g)        BENEFITS.  You and your dependents shall be included in any
                     and all plans, programs and policies which provide benefits
                     for employees and their  dependents.  Such plans,  programs
                     and policies may include health care  insurance,  long-term
                     disability plans, life insurance,  supplemental  disability
                     insurance,  supplemental life insurance, holidays and other
                     similar or comparable  benefits  made  available to Company
                     employees.

           h)        ABSENCES.  You will be  entitled  to  absences  because  of
                     illness  or  other  incapacity,  and such  other  absences,
                     whether  for  holiday,  personal  time,  or for  any  other
                     purpose, as set forth in the Company's employment manual or
                     current  policies and  procedures,  as the case may be. You
                     will be entitled  to four weeks per year of vacation  time,
                     to be taken consistent with the policies of the Company and
                     the effective  discharge of your duties. You will also have
                     the right to  accumulate  such  vacation  time from year to
                     year  as   specified  by  current   Company   policies  and
                     procedures.

           You  will be  subject  to all of the  Company's  other  policies  and
procedures,  including,  without limitation,  the requirement that you execute a
copy  of the  attached  form of (1)  Invention  Assignment  and  Confidentiality
Agreement and (2) Non-Competition Agreement. Further, the Company and you hereby
agree and  acknowledge  that your  employment with the Company is for an initial
term of two years from the date of approval of this offer letter by the Board of
Directors of the Company and,  thereafter,  will not, unless otherwise agreed to
by the  Company  and  you,  be for any  specified  term  but  rather  will be an
"at-will"  relationship  pursuant to which your employment  relationship  may be
terminated  by the Company  with or without  cause.  18 months into the intitial
two-year  term of  agreement,  the  Board  of  Directors  will  give an  initial
indication in writing of their intended actions as it relates to Mr. Weinstein's
employment  status at the end of the initial term.  It is  understood  that this
notification  is not binding on the ultimate  decision but is an  indication  of
intent at that time. During the initial two-year term, however,  your employment
relationship  with the Company may be terminated by the Company upon your death,
disability  (defined as 180 days of disability in a one-year period,  whether or
not such  days are  continuous)  or for  cause  (as  hereinafter  defined).  For
purposes of this offer letter, "cause" is defined as:

                     "The  Company  may  terminate  the  Employee's   employment
           hereunder  for  cause  immediately  and  with  prompt  notice  to the
           Employee, which cause shall be determined in good faith solely by the
           Board of Directors. 'Cause' for termination shall include, but is not
           limited to, the following conduct of the Employee:

     (1) Material  breach of any  provision of this  Agreement by the  Employee,
which breach shall not have been cured by the Employee  within  thirty (30) days
of receipt of written notice of said breach;

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<PAGE>

     (2) Misconduct as an employee of the Company, including but not limited to:
(i)  misappropriating  any funds or property of the Company;  (ii) attempting to
willfully  obtain any personal profit from any transaction in which the Employee
has an interest  which is adverse to the interests of the Company;  or (iii) any
other act or  omission  which  substantially  impairs the  Company's  ability to
conduct its ordinary business in its usual manner;

     (3)  Unreasonable  neglect or refusal to perform the duties assigned to the
Employee under or pursuant to this Agreement;

     (4) Conviction of a felony; or

     (5) Any other act or  omission  which  subjects  the  Company or any of its
subsidiaries to substantial public disrespect, scandal or ridicule."

           If you agree with the stated  provisions,  please  sign and date both
copies  enclosed and return one copy to me. I will copy other Board  members and
Corporate  Counsel.  When you sign this  document,  please provide a copy to Rob
Phillips for his information as well.

                                   Sincerely,

                                   James A. Taylor, Ph.D.

 /s/ James A. Taylor      4/15/98     /s/ Mark L. Weinstein       4/15/98
---------------------     -------    ----------------------       -------
James A. Taylor, Ph.D.     Date      Mark L. Weinstein              Date

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