Group medical practices are defined as "the practice of medicine by a group of physicians who share their premises and other resources."

Largest group medical practices in the United States

The table below shows the top 50 largest group medical practices in the United States, as well as the number of offices in each and the number of practicing physicians in each group.

Rank	Medical Group	Offices	Physicians
1	Kaiser Permanente Medical Group	301	7858
2	Greater Houston Anesthesiology	11	2278
3	Cleveland Clinic	104	1851
4	MEDNAX (f.k.a. Pediatrix/Obstetrix Med Grp Nat)	300	1700
5	Advanced Radiology	19	1349
6	Mayo Clinic Jacksonville	37	1311
7	Fairview Physician Associates	194	1295
8	University Pittsburgh Phys	156	1215
9	Palo Alto Medical Foundation	47	905
10	Partners in Care	?	850
11	Henry Ford Medical Group	60	816
12	Radiology Imaging Associates	14	796
13	Aurora Medical Group	88	790
14	Marshfield Clinic Marshfield Clinic Marshfield Clinic is a health care system in northern, central and western Wisconsin, with 2 hospitals and 52 community care centers as of June, 2010. It was founded in 1916 by six local physicians: K.W. Doege, William Hipke, Victor Mason, Walter G. Sexton, H.H. Milbee, and Roy P...	54	779
15	Austin Radiological Assn	12	754
16	UC Davis Medical Group	68	673
17	ENH Medical Group	133	664
18	Harvard Vanguard Medical Associates Harvard Vanguard Medical Associates Harvard Vanguard Medical Associates is an American non-profit multi-specialty group medical practice operating in eastern Massachusetts. It was founded in the late 1960s as part of Harvard Community Health Plan . The two organizations split in 2004. It is allied with four other regional practices...	23	650
19	Emory Clinic	76	636
20	Geisinger Medical Center	56	616
21	UW Health Clinics	80	612
22	Ochsner Clinic	27	554
23	Allina Medical Clinic Coon Rpds	41	552
24	Carolinas Physician Network	90	539
25	Lsu Healthcare Network Rhu	55	532
26	Park Nicollet Health Services	46	523
27	Lahey Clinic	17	520
28	Scott & White Clinic	26	515
29	Vanderbilt Medical Group	60	499
30	Radiological Assocs Sacramento	14	480
31	Ermed Physicians	1	477
32	University Health Associates	17	476
33	Healthcare Partners Medical Grp	109	458
34	UT Medicine	38	444
35	University Radiology Group	7	443
36	Duluth Clinic	45	440
37	Virginia Mason Clinic	12	437
38	UCSD Medical Group Urology	50	420
39	St John's Clinic	102	418
40	Radia Inc	14	402
41	Northwestern Medical Facility Fdn	30	397
42	Spectrum Health Medical Group	20	394
43	Dartmouth-Hitchcock Manchester	35	389
44	Montefiore Medical Group	38	382
45	Queens Long Island Med Grp	20	376
46	MeritCare	32	374
47	Radiology Alliance	9	372
48	IHC Physician Group	47	364
49	UT Medical Group Inc	39	358
50	Healthpartners	23	353

Office-based physicians and group practices

There are approximately 230,187 physician practices in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. Among these physician practices, 52.8% consist of only one office-based physician. The remaining 47.2% of physician practices are group practices. Physician group practices with 2-5 physicians make up 37.1% of physician offices in the United States. 6.3% consist of 6-9 physicians and the remaining 3.7% consist of 10 or more physicians. The chart below provides a breakdown of all U.S. physician practices, by size of practice.

Office Size	# of Offices	% of Total
1 physician	121,643	52.85%
2 physicians	41,188	17.89%
3-5 physicians	44,186	19.20%
6-9 physicians	14,595	6.34%
10-19 physicians	6,304	2.74%
20+ physicians	2,271	0.99%
Total	230,187	100.00%