Bioanalytical  Systems,  Inc. and Toxicology  Pathology  Services Sign Letter of
Intent

Bioanalytical  Systems, Inc. (NASDAQ: BASI) announced today that it has signed a
letter of intent to purchase Toxicology  Pathology  Services,  Inc. (TPS) of Mt.
Vernon,  IN, pending a detailed business and legal review. TPS has provided high
quality  pre-clinical  research  services to pharmaceutical,  medical device and
other markets for more than 20 years.  The company's  reputation  for scientific
excellence, customer focus and on-time reporting is exemplary.

"Shareholders expect us to build our BAS contract research services business. We
made substantial  investments in our staff,  analytical  equipment and lab space
last year.  That growth  focused on analytical  chemistry in support of clinical
trials for major ethical  pharmaceutical  companies.  It will continue in 2000,"
commented BAS President and CEO, Peter T. Kissinger.

"Acquiring  TPS is an  important  element of our growth  strategy.  Our balanced
development plan demands that we step upstream in pharmaceutical  development to
support  pre-clinical  drug  development for key  pharmaceutical  accounts.  The
proposed acquisition of TPS will give us new technologies, people and facilities
near our core labs to satisfy  clients'  pre-clinical  trial dosing and sampling
needs and clinical trial analysis and reporting requirements."

BAS is also an  industry  leader  in the  development  and  sales of  instrument
systems for monitoring in vivo  biochemistry and physiology.  These systems have
been used by  clients  in new drug  development,  toxicology,  cancer  research,
addiction and behavioral  research.  TPS  technology,  facilities and skill base
will enable BAS to explore new products, uses and services for in vivo systems.

The  50,000-square-foot  TPS facility  includes 40 custom  designed study rooms.
Many meet US Food and Drug  Administration's  GLP  guidelines.  The  facility is
fully accredited by AAALAC.

TPS founder,  Vice President of Research and principal  shareholder Dr. James A.
Botta has agreed to extend his tenure with BAS. Dr. Botta's  credentials include
degrees in Veterinary Medicine, Physiology and Toxicology from Auburn and Purdue
Universities.  He taught courses in Pharmacology,  Toxicology and Anesthesiology
at Auburn and was Principal  Investigator in charge of the toxicology section at
Bristol Myers Squibb Mead Johnson prior to founding TPS.

BAS serves  pharmaceutical and medical device industries,  clinical laboratories
and the basic  research  community  with a wide  variety  of  contract  research
services,      research     equipment     and     diagnostic     kits.     Visit
http://www.bioanalytical.com to learn more about BAS.

This release contains  forward-looking  statements that are subject to risks and
uncertainties,  including but not limited to risks and uncertainties  related to
the  development  of products  and  services,  changes in  technology,  industry
standards and  regulatory  standards,  and various  market and  operating  risks
detailed in the company's  filings with the Securities and Exchange  Commission.