RESTATED

                          CERTIFICATE OF INCORPORATION

                                       OF

                               Unilab Corporation


                  UNILAB CORPORATION,  a Delaware corporation,  hereby certifies
as follows:

                  1. The name of the Corporation is Unilab Corporation. The date
of the filing of its original Certificate of Incorporation with the Secretary of
State of the State of Delaware was September 24, 1990, and the Corporation filed
a  Certificate  of  Amendment  to its  Certificate  of  Incorporation  with  the
Secretary of State of the State of Delaware on May 23, 1991.

                  2. This  Restated  Certificate  of  Incorporation  amends  and
restates the provisions of the Certificate of  Incorporation  of the Corporation
and was duly adopted in accordance  with the  provisions of Sections 242 and 245
of the General Corporation Law of the State of Delaware.

                  3. The text of the Certificate of Incorporation is hereby
amended and restated in its entirety to read as follows:


                                   "ARTICLE I

                                      Name

      The name of the corporation is DPD Holdings Inc. (the "Corporation").


                                   ARTICLE II

                     Registered Office and Registered Agent

                  The address of the registered office of the Corporation in the
State of Delaware is Corporation  Trust Center,  1209 Orange Street, in the City
of Wilmington,  County of New Castle.  The name of the  registered  agent of the
Corporation at such address is The Corporation Trust Company.




                                        1





                                   ARTICLE III

                                Corporate Purpose

                  The purpose of the  Corporation is to engage in any lawful act
or  activity  for  which   corporations  may  be  organized  under  the  General
Corporation Law of the State of Delaware (the "General Corporation Law").


                                   ARTICLE IV

                                  Capital Stock

                  The total  number of shares of all  classes  of stock that the
Corporation  shall  have  authority  to issue is 10,000,  all of which  shall be
shares of Common Stock, par value $.01 per share.


                                    ARTICLE V

                                    Directors

                  SECTION 1. Elections of directors of the Corporation  need not
be by written  ballot,  except and to the extent  provided in the By-laws of the
Corporation.

                  SECTION 2. To the  fullest  extent  permitted  by the  General
Corporation Law as it now exists and as it may hereafter be amended, no director
of  the  Corporation  shall  be  personally  liable  to the  Corporation  or its
stockholders for monetary damages for breach of fiduciary duty as a director.


                                   ARTICLE VI

                Indemnification of Directors, Officers and Others

                  SECTION  1.  The  Corporation  shall  to  the  fullest  extent
permitted by the provisions of the General  Corporation Law of Delaware,  as now
or hereafter in effect,  indemnify all persons whom it may indemnify  under such
provisions.  The  indemnification  provided by this  Section  shall not limit or
exclude any rights,  indemnities or limitations of liability to which any person
may  be  entitled  whether  as a  matter  of  law,  under  the  By-laws  of  the
Corporation,  by agreement,  vote of the stockholders or disinterested directors
of the Corporation or otherwise.



                                        2





                  SECTION 2. The  personal  liability  of the  directors  of the
Corporation is hereby  eliminated to the fullest  extent  permitted by paragraph
(7) of Subsection (b) of Section 102 of the General Corporation Law of Delaware,
as the same may be amended and supplemented.


                                   ARTICLE VII

                                     By-laws

                  The  directors  of the  Corporation  shall  have the  power to
adopt, amend or repeal by-laws.


                                  ARTICLE VIII

                                 Reorganization

                  Whenever a compromise or arrangement is proposed  between this
Corporation  and  its  creditors  or any  class  of  them  and/or  between  this
Corporation  and its  stockholders  or any class of them, any court of equitable
jurisdiction  within the State of Delaware may, on the  application in a summary
way of this  Corporation  or of any  creditor or  stockholder  thereof or on the
application of any receiver or receivers  appointed for this  Corporation  under
the  provisions  of  section  291 of  Title  8 of the  Delaware  Code  or on the
application of trustees in dissolution or of any receiver or receivers appointed
for this  Corporation  under the  provisions  of  section  279 of Title 8 of the
Delaware Code order a meeting of the creditors or class of creditors,  and/or of
the stockholders or class of stockholders of this  Corporation,  as the case may
be, to be summoned in such  manner as the said court  directs.  If a majority in
number  representing  three-fourths  in  value  of the  creditors  or  class  of
creditors,  and/or  of  the  stockholders  or  class  of  stockholders  of  this
Corporation,  as the case may be, agree to any compromise or arrangement  and to
any  reorganization  of this  Corporation as  consequence of such  compromise or
arrangement,  the said  compromise or  arrangement  and the said  reorganization
shall,  if sanctioned by the court to which the said  application has been made,
be  binding  on all the  creditors  or class  of  creditors,  and/or  on all the
stockholders or class of stockholders,  of this Corporation, as the case may be,
and also on this Corporation.





                                        3





                                   ARTICLE IX

                                    Amendment

                  The Corporation  reserves the right to amend, alter, change or
repeal any provision of this Certificate of Incorporation,  in the manner now or
hereafter  prescribed by law, and all rights  conferred on  stockholders in this
Certificate of Incorporation are subject to this reservation."

                  IN  WITNESS  WHEREOF,   DPD  HOLDINGS  INC.  has  caused  this
certificate  to be signed  by  Andrew  H.  Baker,  its  Chairman  of the  Board,
President  and Chief  Executive  Officer,  and  attested  by Mark L.  Bibi,  its
Secretary, as of this 10th day of November, 1993.


                                         UNILAB CORPORATION



                                         By    /s/ Andrew H. Baker
                                           ----------------------------
                                                  Andrew H. Baker
                                              Chairman of the Board,
                                                  President and
                                              Chief Executive Officer

ATTEST:



     /s/ Mark L. Bibi
- ---------------------------
         Mark L. Bibi
         Secretary



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                              CERTIFICATE OF MERGER

                                       OF

                      AMERICAN CLINICAL LABORATORIES, INC.
                        DAMON CLINICAL LABORATORIES, INC.
                    DAMON CLINICAL LABORATORIES-HOUSTON, INC.
                                   MEDLAB INC.
                              MPC LABORATORY, INC.
           NICHOLS INSTITUTE PROFESSIONAL SERVICES ORGANIZATION, INC.
                             NICHOLS GP CORPORATION
                             NICHOLS LP CORPORATION
          NICHOLS INSTITUTE SUBSTANCE ABUSE TESTING LABORATORIES, INC.
                                  PATHLAB, INC.
                                       AND
                           REDWOOD MEDICAL LABORATORY

                                      INTO

                                DPD HOLDINGS INC.

                     Pursuant to Section 252 of the General
                    Corporation Law of the State of Delaware

                                                      * * * *

                  The undersigned hereby certifies that:

         1. The name of and state of  incorporation  of each of the  constituent
corporations are as follows:

                  Name                                 State of Incorporation

         AMERICAN CLINICAL LABORATORIES, INC.          California
         DAMON CLINICAL LABORATORIES, INC.             Texas
         DAMON CLINICAL LABORATORIES -                 Texas
                  HOUSTON, INC.
         MEDLAB INC.                                   Oregon
         MPC LABORATORY, INC.                          Texas
         NICHOLS INSTITUTE PROFESSIONAL                California
                  SERVICES ORGANIZATION, INC.
         NICHOLS GP CORPORATION                        California
         NICHOLS LP CORPORATION                        California
         NICHOLS INSTITUTE SUBSTANCE ABUSE             Delaware


                                        5





                  TESTING LABORATORIES, INC.
         PATHLAB, INC.                                  Texas
         REDWOOD MEDICAL LABORATORY                     California
         DPD HOLDINGS INC.                              Delaware


         2. An  Agreement  and Plan of Merger  dated as of December 6, 1994 (the
"Merger  Agreement")  among  each  of  the  constituent  corporations  has  been
approved,  adopted,  certified,   executed  and  acknowledged  by  each  of  the
constituent  corporations in accordance with the  requirements of Section 252(c)
of the General Corporation Law of the State of Delaware.

         3. The name of the surviving corporation is DPD Holdings Inc.

         4. The Certificate of  Incorporation  of DPD Holdings Inc. in effect at
the effective time of the merger shall be the  Certificate of  Incorporation  of
the surviving corporation.

         5. The surviving corporation is a corporation of the State of Delaware.

         6. The executed  Merger  Agreement is on file at the principal place of
business of the surviving  corporation  at One Malcolm  Avenue,  Teterboro,  New
Jersey 07608.

         7. A copy of the Merger  Agreement  will be furnished by the  surviving
corporation,  on request and without cost, to any stockholder of any constituent
corporation.

         8. The authorized  capital stock of each constituent  corporation which
is not a Delaware corporation is as follows:

                  Name                  Authorized Capital Stock

AMERICAN CLINICAL LABORATORIES, INC.    50,000 shares,            no par value
DAMON CLINICAL LABORATORIES, INC.       1,000 shares,             no par value
DAMON CLINICAL LABORATORIES -           1,000 shares,             no par value
         HOUSTON, INC
MEDLAB, INC.                            375,000 shares,           no par value
MPC LABORATORY, INC                     1,000 shares,           $.01 par value
NICHOLS INSTITUTE PROFESSIONAL          10,000 shares,            no par value
         SERVICES ORGANIZATION, INC.
NICHOLS GP CORPORATION                  1,000 shares,           $.01 par value
NICHOLS LP CORPORATION                  1,000 shares,           $.01 par value
PATHLAB, INC.                           1,000 shares,           $.01 par value
REDWOOD MEDICAL LABORATORY              75,000 shares,         $1.00 par value

         9. That the merger shall become  effective at 9:00 P.M. on December 30,
1994.


                                        6





                  IN  WITNESS  WHEREOF,  this  Certificate  of  Merger  has been
executed on this 6th day of December, 1994.



Attest:                                     DPD HOLDINGS INC.


/s/ Leo C. Farrenkopf, Jr.                  By: /s/ James D. Chambers
- --------------------------                     -------------------------
Leo C. Farrenkopf, Jr.                          James D. Chambers
Secretary                                       Vice President




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