X0305 4 2012-05-08 0001022079 QUEST DIAGNOSTICS INC DGX 0001142624 RUSCKOWSKI STEPHEN H C/O QUEST DIAGNOSTICS INCORPORATED 3 GIRALDA FARMS MADISON NJ 07940 1 1 President and CEO Common Stock 2012-05-08 4 P 0 20000 56.8874 A 63034 D This transaction was executed in multiple purchases at prices ranging from $56.76 to $57.00. The price reported above reflects the weighted average purchase price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. /s/ William J. O'Shaughnessy, Jr., Attorney in Fact for Stephen H. Rusckowski 2012-05-09