EXHIBIT 99.1

FOR IMMEDIATE RELEASE

Contacts:
DIANON Systems, Inc.                Noonan/Russo Communications, Inc.
Kevin C. Johnson                    (212) 696-4455
President and CEO                   Heather Regan (media), ext. 241
(203) 381-4905                      Belinda Brouder (investors), ext. 224
                                    news@noonanrusso.com
David R. Schreiber
Chief Financial Officer
(203) 381-4055

              DIANON SYSTEMS, INC. SIGNS DEFINITIVE AGREEMENT TO
               ACQUIRE ASSETS OF KYTO MERIDIEN DIAGNOSTICS, LLC

Stratford,  CT,  April 8, 1999 - DIANON  Systems,  Inc.  (NASDAQ:  DIAN),  today
announced that it has successfully  completed its due diligence and has signed a
definitive agreement to acquire substantially all of the assets of Kyto Meridien
diagnostics, LLC, an outpatient Ob/Gyn laboratory with locations in Woodbury and
New City,  New York.  The  acquisition  is scheduled to become  effective May 1,
1999.

"The addition of Kyto Meridien to our company will provide substantial  economic
as well as strategic  benefits,"  commented  David  Schreiber,  chief  financial
officer  of DIANON  Systems.  "Kyto's  current  profitability  coupled  with the
projected  synergies  between  our  organizations  should  make the  acquisition
accretive to earnings in the second half of 1999, in addition to increasing  our
1999 sales by approximately $8 million."

As previously  announced,  Kyto Meridien  enjoys an  outstanding  reputation for
clinical  excellence  and  is  recognized   nationally  as  a  premier  cytology
laboratory in the Northeast. Ralph Richart, MD, a world leader in cytology and a
tenured professor at Columbia  University's  College of Physicians and Surgeons,
is the medical  director of Kyto  Meridien and will remain in this capacity with
DIANON.  DIANON  believes  that  Kyto  Meridien's  Ob/Gyn  focus  represents  an
excellent  fit with  DIANON's  full  service  anatomic  pathology  offering  and
enhances DIANON's strategic opportunities on many levels.

DIANON Systems, Inc. provides a full line of anatomic pathology testing services
and a number of genetic and  clinical  chemistry  testing  services to patients,
physicians, and managed care organizations throughout the United States.

The  forward-looking  statements in this news release  relating to  management's
expectations  and beliefs are based on  preliminary  information  and management
assumptions.  Such  forward-looking  statements  are  subject to a wide range of
risks and uncertainties that could cause results to differ in material respects,
including those relating to reimbursement rates and coverage, state and national
regulatory compliance, the Company's maintenance of above-average quality of its
services and products and competitive  pressures.  Further information regarding
factors that could affect the Company's results is included in the Company's SEC
filings, including this year's Form 10-K.