SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM 8-K

                                 CURRENT REPORT
     PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934



                                Date of report:
                       (Date of earliest event reported)
                                  May 23, 2002



                              DIANON Systems, Inc.
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             (Exact name of registrant as specified in its charter)



             Delaware                    000-19392              06-1128081
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   (State or other jurisdiction       (Commission File       (I.R.S. Employer
        of incorporation)                 Number)          Identification No.)



      200 Watson Boulevard, Stratford, Connecticut                06615
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        (Address of principal executive offices)                (Zip Code)



               Registrant's telephone number, including area code
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                                 (203) 381-4000



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         (Former name or former address, if changed since last report.)






ITEM 4.  CHANGES IN REGISTRANT'S CERTIFYING ACCOUNTANT.

            On May 23, 2002, the board of directors of DIANON Systems, Inc. (the
"Company"), upon recommendation of its Audit Committee, decided to dismiss
Arthur Andersen LLP ("Arthur Andersen") as the Company's independent public
accountants, and authorized the engagement of Ernst & Young ("E&Y") to serve as
the Company's independent public accountants for the fiscal year ending December
31, 2002.

            None of Arthur Andersen's reports on the Company's consolidated
financial statements for the fiscal years ended December 31, 2001 and December
31, 2000 contained an adverse opinion or disclaimer of opinion, nor was any such
report qualified or modified as to uncertainty, audit scope or accounting
principles.

            During the Company's two most recent fiscal years ended December 31,
2001 and 2000, and the subsequent interim period through May 23, 2002, there
were no disagreements between the Company and Arthur Andersen on any matters of
accounting principles or practices, financial statement disclosure, or auditing
scope or procedure, which disagreements, if not resolved to Arthur Andersen's
satisfaction, would have caused Arthur Andersen to make reference to the subject
matter of the disagreement in connection with its reports. None of the
reportable events described under Item 304(a)(1)(v) of Regulation S-K occurred
within the two most recent fiscal years ended December 31, 2001, or within the
interim period through the date of this report.

            During the Company's two most recent fiscal years and through the
date of this Form 8-K, the Company did not consult E&Y with respect to the
application of accounting principles to a specified transaction, either
completed or proposed, or the type of audit opinion that might be rendered on
the Company's consolidated financial statements, or any other matters or
reportable events listed in Items 304(a)(2)(i) and (ii) of Regulation S-K.

            The Company provided Arthur Andersen with a copy of the foregoing
disclosures. Attached as Exhibit 16.1 is a copy of Arthur Andersen's letter,
dated May 23, 2002, evidencing its agreement with the statements set forth in
this report.

ITEM 7.  FINANCIAL STATEMENTS, PRO FORMA FINANCIAL INFORMATION AND EXHIBITS

         (c) Exhibits:  The following documents are filed as exhibits to this
                        report:

         16.1  Letter from Arthur Andersen LLP, dated May 23, 2002.


                                    SIGNATURE

            Pursuant to the requirements of the Securities Exchange Act of 1934,
the registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.


                                         DIANON Systems, Inc.


                                         /s/    David R. Schreiber
Date:  May 23, 2002                      ---------------------------------------
                                         Name:  David R. Schreiber
                                         Title: Senior Vice President, Finance
                                                and Chief Financial Officer






                                  EXHIBIT INDEX


      16.1        Letter from Arthur Andersen LLP, dated May 23, 2002