Quest Diagnostics Incorporated , the nation's leading provider of diagnostic testing, information and services, announced that it is scheduled to speak at the Thomas Weisel Partners Healthcare Conference on Thursday, September 7, 2006, at the Four Seasons Boston in Boston, Massachusetts. The Quest Diagnostics presentation is scheduled to begin at 2:05 p.m. Eastern Time.

During the conference, the company will reiterate its 2006 guidance. Excluding the performance of NID, its test kit manufacturing subsidiary, whose operations are being discontinued, the company expects revenue growth of approximately 15%, operating income to approximate 17.5% of revenues, and earnings per diluted share between $2.95 and $3.05.

The presentation will be webcast live during the conference and will be available to registered investors on the following site: http://www.veracast.com/webcasts/twp/healthcare06/82210105.cfm and to the public on http://www.questdiagnostics.com/. In addition, the archived webcast will be available one hour after the live presentation and will remain available until October 7, 2006.

Quest Diagnostics is the leading provider of diagnostic testing, information and services that patients and doctors need to make better healthcare decisions. The company offers the broadest access to diagnostic testing services through its national network of laboratories and patient service centers, and provides interpretive consultation through its extensive medical and scientific staff. Quest Diagnostics is a pioneer in developing innovative new diagnostic tests and advanced healthcare information technology solutions that help improve patient care. Additional company information is available at: www.questdiagnostics.com.

The statements in this press release which are not historical facts or information may be forward-looking statements. These forward-looking statements involve risks and uncertainties that could cause actual results and outcomes to be materially different. Certain of these risks and uncertainties may include, but are not limited to, competitive environment, changes in government regulations, changing relationships with customers, payers, suppliers and strategic partners and other factors described in the Quest Diagnostics Incorporated 2005 Form 10-K and subsequent SEC filings.

SOURCE: Quest Diagnostics Incorporated

CONTACT: Laure Park, Investors, +1-201-393-5030, or Gary Samuels, Media,
+1-201-393-5700, both of Quest Diagnostics Incorporated

Web site: http://www.questdiagnostics.com/