FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * PREVOZNIK MICHAEL E   2. Issuer Name and Ticker or Trading Symbol QUEST DIAGNOSTICS INC [DGX] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) Senior VP & General Counsel (Last) (First) (Middle) 1290 WALL STREET WEST 3. Date of Earliest Transaction (Month/Day/Year) 05/11/2006 (Street) LYNDHURST, NJ 07071 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 05/11/2006   S   6,000 D $ 58.0266 19,952 D   Common Stock 05/12/2006   M   41,000 A $ 6.585 60,952 D   Common Stock 05/12/2006   S   36,320 D $ 57.8797 24,632 D   Common Stock 05/12/2006   F   4,665 D $ 57.8797 19,967 (1) D   Common Stock 05/11/2006   I   2,924 A $ 57.7 4,157 (2) I 401(k)/SDCP

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Stock Options (Right to buy)

$ 6.585

05/12/2006

M

41,000

08/16/2000

08/16/2009

Common Stock

41,000

$ 0

104

D

Stock Options (Right to buy)

$ 57.8797

05/12/2006

A

4,665

05/12/2007

08/16/2009

Common Stock

4,665

$ 0

4,665

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
PREVOZNIK MICHAEL E 1290 WALL STREET WEST LYNDHURST, NJ 07071			Senior VP & General Counsel

Signatures

Leo C. Farrenkopf Jr. atty-in-fact for Michael E. Prevoznik		05/15/2006
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	On June 20, 2005, the Company effected a 2-for-1 stock split of its Common Stock in the form of a 100% stock dividend. All prior holdings, including stock options, have been adjusted to reflect the stock split. The amount also includes exempt purchases made under the Company's stock purchase plan since the date of the last filing on Form 4.
(2)	Subject to the discretionary transaction reported herein, the underlying shares were acquired on a periodic basis by the trustee of the Company's tax qualified Profit Sharing (401(k) and/or Supplemental Deferred Compensation plan. The information was obtained from the plan administrator as of a recent date. The number of shares is based on the account balance of the Company stock fund under the plan (which includes some money market instruments) divided by the market price of the Company's stock as of that date.

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