POWER OF ATTORNEY


	Know all by these presents, that the undersigned
hereby constitutes and appoints each of Sirisha Gummaregula,
Michael E. Prevoznik, and Leo C. Farrenkopf, Jr., signing
singly, the undersigned's true and lawful attorney-
in-fact to:

(1)	execute for and on behalf of the undersigned, in
the undersigned's capacity as an executive officer and/or
director of Quest Diagnostics Incorporated (the "Company"),
Form ID Applications and Forms 3, 4 and 5 in accordance
with Section 16(a) of the Securities Exchange Act of 1934
and the rules thereunder;

(2)	do and perform any and all acts for and on behalf
of the undersigned which may be necessary or desirable to
complete and execute any such Form ID Application, Form 3,
4 or 5, complete and execute any amendment or amendments
thereto, and timely  file such form with the United States
Securities and Exchange Commission and any other authority;
and

(3)	take any other action of any type whatsoever in
connection with the foregoing which, in the opinion of
such attorney-in-fact, may be of benefit to, in the best
interest of, or legally required by, the undersigned, it
being understood that the documents executed by such
attorney-in-fact on behalf of the  undersigned pursuant
to this Power of Attorney shall be in such form and shall
contain such terms and conditions as such attorney-in-fact
may approve in such attorney-in-fact's discretion.

	The undersigned hereby grants to each such attorney-
in-fact full power and authority to do and perform all and
every act and thing whatsoever requisite, necessary and
proper to be done in the exercise of any of the rights and
powers herein granted, as fully to all intents and purposes
as the undersigned might or could do if personally present,
with full power of substitution or revocation, hereby
ratifying and confirming all that such attorney-in-fact,
or such attorney-in-fact's substitute or substitutes, shall
lawfully do or cause to be done by virtue of this power of
attorney and the rights and powers herein granted.  The
undersigned acknowledges that the foregoing attorneys-in
- -fact, in serving in such capacity at the request of the
undersigned, are not assuming, nor is the company assuming,
any of the undersigned's responsibilities to comply with
Section 16 of the Securities Exchange Act of 1934.

	This Power of Attorney shall remain in full force
and effect until the undersigned is no longer required to
file Forms 3, 4, and 5 with respect to the undersigned's
holdings of and transactions in securities issued by the
Company, unless earlier revoked by the undersigned in a
signed writing delivered to the foregoing attorneys-in-fact.

	IN WITNESS WHEREOF, the undersigned has caused this
Power of Attorney to be executed as of this 13th day of
April 2004.



	/s/John B. Ziegler
	Signature
	JOHN B. ZIEGLER




STATE OF NEW JERSEY	)
	 		):  ss.
COUNTY OF CAMDEN	)

	On this 13th day of April, 2004, before me, the
subscriber, personally appeared JOHN B. ZIEGLER, to me and
known to me to be the same person described in and who
executed the foregoing instrument, and he duly acknowledged
to me that the executed the same.


	/s/Diane Campellone
	Notary Public
	Notary Public of New Jersey
	My Commission Expires January 9, 2006