Exhibit 21.1

As of December 31, 2005

Quest Diagnostics Incorporated (DE)
(Incorporated on December 12, 1990 in Delaware; FEIN No. 16-1387862)

Subsidiaries and Joint Ventures

100%	Quest Diagnostics Holdings Incorporated (f/k/a SBCL, Inc.) (DE)
	100%	Quest Diagnostics Clinical Laboratories, Inc. (f/k/a SmithKline Beecham Clinical Laboratories, Inc.) (DE)
		(33-l/3%)	Compunet Clinical Laboratories (OH)
		(44%)	Mid America Clinical Laboratories (IN)
		(51%)	Diagnostic Laboratory of Oklahoma LLC (OK)
100%	Quest Diagnostics Incorporated (CA)
100%	Quest Diagnostics Incorporated (MD)
	100%	Diagnostic Reference Services Inc. (MD)
		100%	Pathology Building Partnership (MD) (gen. ptnrshp.)
100%	Quest Diagnostics Incorporated (MI)
100%	Quest Diagnostics Investments Incorporated (DE)
	100%	Quest Diagnostics Finance Incorporated (DE)
100%	Quest Diagnostics LLC (IL)
100%	Quest Diagnostics LLC (MA)
100%	Quest Diagnostics LLC (CT)
100%	Unilab Corporation (DE)
	100%	Unilab Acquisition Corporation, d/b/a FNA Clinics of America (DE)
100%	Quest Diagnostics of Pennsylvania Inc. (DE)
	51%	Quest Diagnostics Venture LLC (PA)
	53.5%	Associated Clinical Laboratories (PA) (gen. ptnrshp.)
		100%	North Coast General Services, Inc. (PA)
100%	Quest Diagnostics of Puerto Rico, Inc
100%	Quest Diagnostics Receivables Inc. (DE)
100%	Quest Diagnostics Ventures LLC (DE)
100%	DPD Holdings, Inc. (DE)
	100%	MetWest Inc. (DE)
		100%	Diagnostic Path Lab, Inc. (TX)
		100%	Quest Diagnostics Provider Network, LLC (CO)
		49%	Sonora Quest Laboratories LLC (AZ)
100%	American Medical Laboratories, Incorporated (DE)
	100%	AML Inc. (DE)
		100%	Quest Diagnostics Nichols Institute, Inc. (f/k/a Medical Laboratories Corporation) (VA)
		100%	Quest Diagnostics Incorporated (NV)
			100% APL Properties Limited Liability Company (NV)
100%	Lab Portal, Inc. (DE)
100%	LabOne, Inc. (MO)

	100%	ExamOne World Wide, Inc. (PA)
		100%	ExamOne World Wide of NJ, Inc. (NJ)
	100%	Systematic Business Services, Inc. (MO)
		100%	Scan Tech Solutions, LLC (MO)
	100%	LabOne, L.L.C. (KS)
	100%	Central Plains Holdings, Inc. (KS)
		100%	Central Plains Laboratories, LLC (KS)
	100%	LabOne Canada, Inc. (Ontario)
		100%	ExamOne Canada, Inc. (Ontario)
			100% Rapid-Med Plus Franchise Corporation (Ontario)
	100%	LabOne of Ohio, Inc. (DE)
	100%	Osborn Group, Inc. (DE)
		100%	Intellisys, Inc. (GA)
100%	Lifepoint Medical Corporation (DE)
	100%	C&S Clinical Laboratory, Inc. (d/b/a Clinical Diagnostic Services) (NJ)
100%	MedPlus, Inc. (OH)
	100%	Worktiviti, Inc. (f/k/a Universal Document Management Systems, Inc.) (OH)
	100%	Valcor Associates Inc. (PA)
100%	Nichols Institute Diagnostics (CA)
100%	Nichols Institute Diagnostics Limited (UK)
100%	Nichols Institute Diagnostics Trading AG (Switzerland)
100%	Nichols Institute Diagnostika GmbH (Germany)
	100%	Nichols Institute Diagnostika GmbH (Austria)
100%	Nichols Institute International Holding B.V. (Netherlands)
	100%	Nichols Institute Diagnostics B.V. (Netherlands)
	100%	Nichols Institute Diagnostics SARL (France)
100%	Nomad Massachusetts, Inc. (MA)
	100%	Quest Diagnostics, S.A. de C.V. (Mexico)
	100%	Analisis, S.A. (Mexico)
	100%	Laboratorios Clinicos de Mexico, S.A. de C.V. (Mexico)
		100%	Servicios de Laboratorio, S.A. de C.V. (Mexico)
	100%	Laboratorios de Frontera Polanco, S.A. de C.V. (Mexico)
	100%	Laboratorio de Analisis Biomedicos, S.A. (Mexico)
100%	Quest Diagnostics do Brasil Ltda. (Brazil)
100%	Quest Diagnostics Limited (UK)
	100%	The Pathology Partnership plc (UK)

2