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Healthcare Insights

Top clinical laboratories by medical lab procedure volume

Clinical medical laboratories are healthcare facilities that provide a wide range of laboratory procedures that help healthcare providers diagnose, treat, and manage patient health. These facilities may also be referred to as medical testing labs.

What role do clinical laboratories play in healthcare?

Clinical laboratories perform blood draws and tests on specimens collected from patients. They can be located within a hospital or outpatient clinic facility or be a free-standing location.

Data reports from the laboratories are entered into a laboratory information system (LIS) which is a platform that processes, manages, and stores the patients’ lab data. The LIS can send orders for analysis, receive test orders, check test quality, track orders and results, and send results to EHR systems for providers and patients to access.

Clinical lab technicians, those who collect and test patient samples, are a crucial part of the care team and help diagnose health conditions based on the test sample.

Diagnostic laboratory corporations, as well as medical device and medical supply companies, use data on these lab facilities to understand their competitive landscape or discover new markets.

Below, we’ve listed the top 20 clinical medical laboratories in the U.S. by procedure volume. The data is from the Atlas All-Payor Claims products for the calendar year 2024.

Top 20 laboratory locations by procedure volume

RankBilling facilityFacility NPIFacility cityFacility state% of 2024 lab proceduresExplore dataset
1UNILAB CORPORATION1366479099WEST HILLSCA11.09%Explore
2QUEST DIAGNOSTICS INCORPORATED1932145778CLIFTONNJ5.54%Explore
3LABORATORY CORPORATION OF AMERICA1659352276SAN DIEGOCA3.58%Explore
4QUEST DIAGNOSTICS CLINICAL LABORATORIES INC1891731626TAMPAFL3.25%Explore
5ACCU REFERENCE MEDICAL LAB, LLC1225110497LINDENNJ2.54%Explore
6SHERMAN ABRAMS LABORATORY INC1598820235BROOKLYNNY2.39%Explore
7EMPIRE CITY LABORATORIES, INC1053584482BROOKLYNNY2.15%Explore
8UNILAB CORPORATION1619913449SACRAMENTOCA2.06%Explore
9LABORATORY CORPORATION OF AMERICA1104829159BURLINGTONNC1.79%Explore
10QUEST DIAGNOSTICS LLC IL1881630614WOOD DALEIL1.74%Explore
11QUEST DIAGNOSTICS CLINICAL LABORATORIES INC1932166386TUCKERGA1.63%Explore
12QUEST DIAGNOSTICS CLINICAL LABORATORIES INC1518903350MIRAMARFL1.56%Explore
13MILLENNIUM HEALTH, LLC1497933162SAN DIEGOCA1.45%Explore
14CLINICAL PATHOLOGY LABORATORIES, INC.1194769497AUSTINTX1.37%Explore
15INTERPATH LABORATORY, INC.1548208440PENDLETONOR1.36%Explore
16HEALTHTRACKRX INDIANA, INC1689639544DENTONTX1.32%Explore
17QUEST DIAGNOSTICS CLINICAL LABORATORIES INC1790721538IRVINGTX1.30%Explore
18LABONE LLC1609812445LENEXAKS1.17%Explore
19QUEST DIAGNOSTICS INCORPORATED1043256886LAS VEGASNV1.06%Explore
20PERMANENTE MEDICAL GROUP, INC.1851454011RICHMONDCA1.05%Explore

Fig. 1 Data is from the Definitive Healthcare PhysicianView and Atlas All-Payor Claims products for calendar year 2024. Claims data is sourced from multiple medical clearinghouses in the U.S. and is updated monthly. Accessed July 2025.

What is the top clinical medical laboratory?

Unilab Corporation, headquartered in West Hills, California, was the clinical medical laboratory with the highest 2025 procedure volume, according to our data. This lab performed 11.09% of clinical laboratory procedures tracked.

In second place is the Quest Diagnostics Incorporated location in Clifton, New Jersey, which performed 5.54% of the lab procedures tracked in 2024. Laboratory Corporation of America’s San Diego facility came in third with 3.58% of total procedure volume.

The list of these 20 clinical medical laboratories is representative of where testing is billed and does not include collection sites. While laboratory testing is not exclusively performed in these clinical medical laboratories, these labs are the most prevalent vendors for handling large volumes of testing procedures.

Some laboratory companies including Quest Diagnostics, Laboratory Corporation of America, and Unilab Corporation operate multiple laboratory locations under different NPI numbers. As such, these companies appear multiple times on this list, and their listed procedure shares reflect individual locations rather than the entire company.

Learn more

Read about how medical device and medical supply companies use data from the Definitive Healthcare platform to better segment and target their healthcare accounts.

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