Item 1.01. Entry into a Material Definitive Agreement

On November 21, 2005, Quest Diagnostics Incorporated (the “Company”), LabOne, Inc., ExamOne World Wide, Inc., ExamOne World Wide of NJ, Inc., Central Plains Holdings, Inc., Central Plains Laboratories, LLC, LabOne of Ohio, Inc., Osborn Group, Inc. and Systematic Business Services, Inc. (collectively the “Additional Subsidiary Guarantors), certain of the Company’s subsidiaries and The Bank of New York, as Trustee, entered into the Seventh Supplemental Indenture. The Seventh Supplemental Indenture supplements the indenture dated as of June 27, 2001 among the guarantors (as defined therein) and the Trustee, as subsequently supplemented by a first supplemental indenture, dated as of June 27, 2001, as further supplemented by a second supplemental indenture, dated as of November 26, 2001, as further supplemented by a third supplemental indenture, dated as of April 4, 2002, as further supplemented by a fourth supplemental indenture, dated as of March 19, 2003, as further supplemented by a fifth supplemental indenture, dated as of April 16, 2004 and further supplemented by a sixth supplemental indenture dated October 31, 2005 (collectively, the “Indenture”).

The Seventh Supplemental Indenture adds the Additional Subsidiary Guarantors, certain of the companies acquired as part of the previously announced LabOne acquisition, as guarantors to the Company’s 6¾% Senior Notes due 2006, 7½% Senior Notes due 2011, 5.125% Senior Notes due 2010 and 5.45% Senior Notes due 2015 issued pursuant to the Indenture. The Seventh Supplemental Indenture is attached hereto as exhibit 4.1.

Item 9.01. Financial Statements and Exhibits