EXHIBIT 99.1


[LABCORP LOGO]
Laboratory Corporation of America

                                   Laboratory Corporation of America(R) Holdings
                                   358 South Main Street
                                   Burlington, NC 27215
                                   Telephone: 336-584-5171


FOR IMMEDIATE RELEASE
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LABCORP CONTACT: 336-436-4855        LABCORP SHAREHOLDER DIRECT: 800-LAB-0401
                 PAMELA SHERRY                                   WWW.LABCORP.COM
                 Investor@labcorp.com

DIANON CONTACT:  KEVIN C. JOHNSON
                 203-381-4000
                 johnsk@DIANON.com


            LABORATORY CORPORATION OF AMERICA(R) ANNOUNCES DEFINITIVE
                    AGREEMENT TO ACQUIRE DIANON SYSTEMS, INC.


BURLINGTON, NC AND STRATFORD, CT, NOVEMBER 11, 2002 -- Laboratory Corporation of
America(R) Holdings (LabCorp(R)) (NYSE: LH) and DIANON Systems, Inc. (NASDAQ:
DIAN), a leading provider of cancer and genomic diagnostic services, today
announced that they have entered into a definitive agreement under which LabCorp
will acquire all of the outstanding shares of DIANON for $47.50 per share in
cash. The transaction, which is subject to DIANON shareholder and regulatory
approval, is expected to close in the first quarter of 2003.

The acquisition is anticipated to be accretive to LabCorp's 2003 diluted
earnings per share by approximately $0.05. LabCorp expects to realize an
estimated $35 million in annual cost savings synergies by year-end 2005.

Under the terms of the agreement, which was unanimously approved by the boards
of both companies, LabCorp will acquire DIANON through a merger of a
newly-formed wholly-owned subsidiary of LabCorp with DIANON. In the merger,
holders of DIANON common stock will receive $47.50 per share, or approximately
$598 million. DIANON currently has approximately 12.6 million fully diluted
shares outstanding. The transaction will be funded by a combination of cash on
hand, borrowings under LabCorp's existing credit facility and a new bridge loan
facility.

DIANON is a leading provider of anatomic pathology and oncology testing services
in the U.S., with a focus on the outpatient market. Approximately 1,100
employees process more than 8,000 samples per day in one main testing facility
and four regional labs. DIANON had 2001 revenues of approximately $126 million,
and revenues of approximately $141 million for the nine-month period ended
September 30, 2002.

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"We are truly excited to have reached an agreement with this premier oncology
testing laboratory," said Thomas P. Mac Mahon, LabCorp's chairman and chief
executive officer. "The proposed acquisition of DIANON is a key part of
LabCorp's strategy to be a leading cancer diagnostic laboratory in North America
offering the most innovative technologies available. This strategy is clearly
supported by DIANON's talented managers and employees, who have substantial
testing expertise, sales capabilities and skill in the development of novel
reporting formats."

"More and better cancer diagnostics will continue to have a profound impact on
patient care in the coming years," continued Mr. Mac Mahon. "Combining LabCorp
and DIANON will improve access to today's valuable cancer testing methods. The
combination will also create a company well positioned to offer innovative new
genomic tests for cancer through its partnerships with technology leaders such
as Myriad Genetics, Inc., EXACT Sciences Corporation, Celera Diagnostics and
Correlogics Systems, Inc."

"We are pleased to announce a transaction with a company that has been a pioneer
in bringing leading-edge technologies to the market," said Kevin C. Johnson,
DIANON's chairman, president and chief executive officer. "LabCorp's focus on
cancer diagnostics and its vast capabilities in specialized testing will help
ensure that our customers continue to receive the very best in testing services.
Opportunities for employees will be available as part of a stronger, more
competitive company."

LabCorp will host a conference call with investors to discuss the transaction on
November 11, 2002 at 11:00 A.M. ET. A live webcast of the call will be available
online at www.labcorp.com or at www.streetevents.com beginning at 11:00 A.M. ET,
with an online rebroadcast continuing through December 11, 2002. The live call
at 11:00 A.M. is also available in a listen-only mode by dialing 212-896-6075. A
telephone replay of the call will be available through November 18, 2002, and
can be heard by dialing 800-633-8284 (402-977-9140 for international callers).
The access code for the replay is 210-33-171.

Analysts and investors are also directed to the home page of LabCorp's website,
www.labcorp.com, where additional information on the DIANON transaction will be
posted. This supplemental information will be filed as an 8-K with the SEC as
soon as the SEC reopens following the Veteran's Day federal holiday.

ABOUT DIANON

DIANON provides a full line of anatomic and molecular pathology testing services
and the CarePath(TM) Health Information Service, which provides personalized,
diagnosis-specific information to physicians and their patients at critical
moments in the healthcare process. DIANON has more than 650 managed care
contracts and over 14,500 physician customers use DIANON's services, including
5,000 of the country's 7,500 urologists. The company has labs in Connecticut,
New York, Florida, Texas and Oklahoma, along with a centralized specimen
processing center in Ohio. Further information about DIANON can be obtained from
the Company's web sites at www.DIANON.com or www.carepathonline.com.

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ABOUT LABCORP

The first national clinical laboratory to fully embrace genomic testing,
Laboratory Corporation of America(R) Holdings (LabCorp(R)) has been a pioneer in
commercializing new diagnostic technologies. As a national laboratory with
annual revenues of $2.2 billion in 2001 and over 25,000 employees, the Company
offers more than 4,000 clinical tests ranging from routine analyses to
sophisticated molecular diagnostics. Serving over 200,000 clients throughout
North America, LabCorp combines its expertise in innovative clinical testing
technology with its Centers of Excellence. The Center for Molecular Biology and
Pathology, in Research Triangle Park, North Carolina, offers state-of-the-art
molecular gene-based testing in infectious disease, oncology and genetics. Its
National Genetics Institute in Los Angeles is an industry leader in developing
novel, highly sensitive polymerase chain reaction (PCR) methods for testing
hepatitis C and other blood borne infectious agents. LabCorp's Minneapolis-based
ViroMed offers molecular microbial testing using real time PCR platforms, while
its Center for Esoteric Testing in Burlington, North Carolina, performs the
largest volume of specialty testing in the network. LabCorp's clients include
physicians, state and federal government, managed care organizations, hospitals,
clinics, pharmaceutical and Fortune 1000 companies, and other clinical
laboratories.

FOR LABCORP INVESTORS

Each of the above forward-looking statements is subject to change based on
various important factors, including without limitation, competitive actions in
the marketplace and adverse actions of governmental and other third-party
payors. Actual results could differ materially from those suggested by these
forward-looking statements. Further information on potential factors that could
affect LabCorp's financial results is included in the Company's Form 10-K for
the year ended December 31, 2001 and subsequent SEC filings.

FOR DIANON INVESTORS

This press release may contain "forward-looking statements" within the meaning
of Section 21E of the Securities Exchange Act of 1934. When used in this press
release, the words "may," "could," "should," "would," "believe," "anticipate,"
"estimate," "expect," "intend," "plan" and similar expressions or statements
regarding future periods are intended to identify forward-looking statements.
All forward-looking statements are inherently uncertain as they are based on
various expectations and assumptions concerning future events, which by their
nature involve substantial risks and uncertainties beyond DIANON Systems, Inc.'s
control. DIANON Systems, Inc. undertakes no obligation to update or revise any
forward-looking statement for events or circumstances after the date on which
such statement is made. DIANON Systems, Inc. cannot assess the impact of or the
extent to which any single factor or risk, or combination of them, may cause
actual results to differ materially from those contained in any forward-looking
statements. For a more complete discussion of risk factors, please see DIANON
Systems, Inc.'s filings with the Securities and Exchange Commission, including
its Annual Report on Form 10K for the year ended December 31, 2001.

DIANON WILL FILE A PROXY STATEMENT AND DIANON AND LABCORP WILL FILE OTHER
RELEVANT DOCUMENTS WITH THE SEC CONCERNING THE PROPOSED MERGER OF A WHOLLY-OWNED
SUBSIDIARY OF LABCORP WITH AND INTO DIANON. INVESTORS ARE URGED TO READ THE
PROXY STATEMENT WHEN IT BECOMES AVAILABLE AND ANY OTHER RELEVANT DOCUMENTS FILED
WITH THE SEC BECAUSE THEY WILL

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CONTAIN IMPORTANT INFORMATION. YOU WILL BE ABLE TO OBTAIN THE DOCUMENTS FREE OF
CHARGE AT THE WEBSITE MAINTAINED BY THE SEC AT WWW.SEC.GOV. IN ADDITION, YOU MAY
OBTAIN DOCUMENTS FILED WITH THE SEC BY LABCORP FREE OF CHARGE BY REQUESTING THEM
IN WRITING FROM LABCORP AT 430 SOUTH SPRING STREET, 1ST FLOOR, BURLINGTON, NORTH
CAROLINA 27215, ATTENTION: INVESTOR RELATIONS, OR BY TELEPHONE AT (336)
229-1127. YOU MAY OBTAIN DOCUMENTS FILED WITH THE SEC BY DIANON FREE OF CHARGE
BY REQUESTING THEM IN WRITING FROM DIANON, 200 WATSON BOULEVARD, STRATFORD,
CONNECTICUT 06615, ATTENTION: SECRETARY, OR BY TELEPHONE AT (203) 381-4055.

LABCORP AND DIANON, AND THEIR RESPECTIVE DIRECTORS AND EXECUTIVE OFFICERS, MAY
BE DEEMED TO BE PARTICIPANTS IN THE SOLICITATION OF PROXIES FROM THE
STOCKHOLDERS OF DIANON IN CONNECTION WITH THE MERGER. INFORMATION ABOUT THE
DIRECTORS AND EXECUTIVE OFFICERS OF LABCORP AND THEIR OWNERSHIP OF LABCORP
SHARES IS SET FORTH IN THE PROXY STATEMENT FOR LABCORP'S 2001 ANNUAL MEETING OF
SHAREHOLDERS FILED WITH THE SEC ON APRIL 15, 2002. INFORMATION ABOUT THE
DIRECTORS AND EXECUTIVE OFFICERS OF DIANON AND THEIR OWNERSHIP OF DIANON STOCK
IS SET FORTH IN THE PROXY STATEMENT FOR DIANON'S 2002 ANNUAL MEETING OF
STOCKHOLDERS FILED WITH THE SEC ON JULY 1, 2002. INVESTORS MAY OBTAIN ADDITIONAL
INFORMATION REGARDING THE INTERESTS OF SUCH PARTICIPANTS BY READING THE PROXY
STATEMENT WHEN IT BECOMES AVAILABLE.

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