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                                                                    Exhibit 31.1

              CERTIFICATION OF CHIEF EXECUTIVE OFFICER PURSUANT TO
                 SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002

I, Kenneth W. Freeman, certify that:

1. I have reviewed this annual report on Form 10-K of Quest Diagnostics
   Incorporated;

2. Based on my knowledge, this annual report does not contain any untrue
   statement of a material fact or omit to state a material fact necessary to
   make the statements made, in light of the circumstances under which such
   statements were made, not misleading with respect to the period covered by
   this annual report;

3. Based on my knowledge, the financial statements, and other financial
   information included in this annual report, fairly present in all material
   respects the financial condition, results of operations and cash flows of the
   registrant as of, and for, the periods presented in this annual report;

4. The registrant's other certifying officers and I are responsible for
   establishing and maintaining disclosure controls and procedures (as defined
   in Exchange Act Rules 13a-15(e) and 15d-15(e)) for the registrant and have:

   a) designed such disclosure controls and procedures, or caused such
      disclosure controls and procedures to be designed under our supervision,
      to ensure that material information relating to the registrant, including
      its consolidated subsidiaries, is made known to us by others within those
      entities, particularly during the period in which this annual report is
      being prepared;

   b) evaluated the effectiveness of the registrant's disclosure controls and
      procedures and presented in this annual report our conclusions about the
      effectiveness of the disclosure controls and procedures, as of the end of
      the period covered by this report based on such evaluation; and

   c) disclosed in this annual report any change in the registrant's internal
      control over financial reporting that occurred during the registrant's
      most recent fiscal quarter (the registrant's fourth fiscal quarter in the
      case of an annual report) that has materially affected, or is reasonably
      likely to materially affect, the registrant's internal control over
      financial reporting; and

5. The registrant's other certifying officers and I have disclosed, based on our
   most recent evaluation of internal control over financial reporting, to the
   registrant's auditors and the audit committee of registrant's board of
   directors (or persons performing the equivalent functions):

   a) all significant deficiencies and material weaknesses in the design or
      operation of internal control over financial reporting which are
      reasonably likely to adversely affect the registrant's ability to record,
      process, summarize and report financial information; and

   b) any fraud, whether or not material, that involves management or other
      employees who have a significant role in the registrant's internal control
      over financial reporting.

February 26, 2004

By /s/ Kenneth W. Freeman
   ----------------------
       Kenneth W. Freeman
       Chairman of the Board and
       Chief Executive Officer