According to Definitive Healthcare data, there are over 136,000 active physician group practices in the U.S., ranging in size from 1-physician solo practices to 8,700-physician practices. Group practices, like those included in the following lists, are generally divided into two categories: single-specialty and multi-specialty. Some physicians work solely as part of a physician group practice, though dual-employment between a group practice and hospital or other care facility is not uncommon.

Independent physician group practices offer greater scheduling flexibility and financial security to physicians than solo physician practices, as well as more employee benefits like health insurance. The larger size of a physician group practice means a wider patient population, allowing physicians to accept greater financial risk in the form of high-risk patients and specialized procedures. Though physician group practices can be a more reliable employment choice than a solo practice, they may not offer as much support in managing administrative tasks and financial risks as hospitals and other traditional care facilities.

The following tables list the largest physician groups by number of physicians and the top physician groups by Medicare charges. According to Definitive Healthcare data, the 25 largest groups by physicians employ over 92,000 physicians, with a total over $20.5 billion in Medicare charges. Meanwhile, the largest physician groups by Medicare charges employ just over 44,000 total physicians, reporting over $28.2 billion in Medicare charges.

Top 25 Physician Groups by Number of Physicians

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Physician Group NameDefinitive IDNumber of PhysiciansMedicare ChargesMain SpecialityExplore This Dataset
1. The Permanente Medical Group 550751 8,679 $227,313,941 Internal Medicine Explore This Profile
2. Southern California Permanente Medical Group 550748 8,151 $228,212,819 Internal Medicine Explore This Profile
3. Hill Physicians Medical Group IPA 550737 3,639 $1,760,739,510 Internal Medicine Explore This Profile
4. University of Pittsburgh Physicians 550835 3,245 $580,664,009 Internal Medicine Explore This Profile
5. Northwell Health Physician Partners 550489 2,994 $1,270,116,960 Emergency Medicine Explore This Profile
6. Cleveland Clinic 618513 2,994 $1,391,422,927 Internal Medicine Explore This Profile
7. Mayo Clinic Physicians 550420 2,823 $454,361,516 Diagnostic Radiology Explore This Profile
8. NYC University Physicians Network 577713 2,761 $1,370,098,883 Internal Medicine Explore This Profile
9. University of Michigan Medical Group 550671 2,718 $552,971,545 Internal Medicine Explore This Profile
10. HealthCare Partners IPA 92755 2,508 $1,684,976,557 Internal Medicine Explore This Profile
11. Massachusetts General Physicians Organization 550418 2,387 $751,873,640 Internal Medicine Explore This Profile
12. University of Penn Medical Group 697339 2,318 $737,669,858 Internal Medicine Explore This Profile
13. University of Washington Physicians 551153 2,272 $299,368,616 Internal Medicine Explore This Profile
14. UCLA Medical Group 609686 2,212 $1,101,906,620 Internal Medicine Explore This Profile
15. University of Colorado Medicine 550933 2,177 $492,834,123 Anesthesiology Explore This Profile
16. Stanford Hospitals and Clinics 706374 2,129 $687,719,791 Anesthesiology Explore This Profile
17. Ascension Medical Group 717580 2,111 $534,897,628 Family Practice Explore This Profile
18. Regal Medical Group 552260 2,083 $463,062,676 Family Practice Explore This Profile
19. Christus Physician Group 746511 2,074 $1,334,104,391 Pediatric Medicine Explore This Profile
20. Allina Health System Physicians 550231 2,058 $553,241,842 Family Practice Explore This Profile
21. Brigham and Womens Physicians Organization 550263 2,035 $522,273,183 Internal Medicine Explore This Profile
22. Duke Health Providers 630957 2,031 $676,263,171 Internal Medicine Explore This Profile
23. Geisinger Clinic Physician Group 550339 2,012 $867,859,377 Internal Medicine Explore This Profile
24. Aurora Health Care Medical Group Inc.550238 1,926 $1,462,141,839 Family Practice Explore This Profile
25. Advocate Medical Group 550221 1,888 $533,925,859 Internal Medicine Explore This Profile

Fig 1. Data from Definitive Healthcare based on the most recent CMS Physicians Compare File as of August 2019

Top 25 Physician Groups by Medicare Charges

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Physician Group NameDefinitive IDPhysiciansMedicare ChargesMain SpecialtyExplore This Dataset
1. Texas Oncology 553058 467 $2,346,994,995 Hematology/Oncology Explore This Profile
2. Florida Cancer Specialists and Research Institute 551855 226 $1,964,307,601 Hematology/Oncology Explore This Profile
3. Hill Physicians Medical Group IPA 550737 3,639 $1,760,739,510 Internal Medicine Explore This Profile
4. HealthCare Partners IPA 92755 2,508 $1,684,976,557 Internal Medicine Explore This Profile
5. Aurora Health Care Medical Group Inc 550238 1,926 $1,462,141,839 Family Practice Explore This Profile
6. Cleveland Clinic 618513 2,994 $1,391,422,927 Internal Medicine Explore This Profile
7. NYC University Physicians Network 577713 2,761 $1,370,098,883 Internal Medicine Explore This Profile
8. Arizona State Physicians Association 552274 1,311 $1,366,183,609 Pediatric Medicine Explore This Profile
9. Christus Physician Group 746511 2,074 $1,334,104,391 Pediatric Medicine Explore This Profile
10. US Anesthesia Partners 552756 1,791 $1,303,332,869 Anesthesiology Explore This Profile
11. Northwell Health Physician Partners 550489 2,994 $1,270,116,960 Emergency Medicine Explore This Profile
12. UCLA Medical Group 609686 2,212 $1,101,906,620 Internal Medicine Explore This Profile
13. North American Partners in Anesthesia 955536 1,198 $948,029,762 Anesthesiology Explore This Profile
14. 21st Century Oncology 956277 324 $938,864,079 Radiation Oncology Explore This Profile
15. Geisinger Clinic Physician Group 550339 2,012 $867,859,377 Internal Medicine Explore This Profile
16. Lifebridge Health Physicians 602442 1,465 $811,047,080 Internal Medicine Explore This Profile
17. IPA of Nassau & Suffolk Counties 552273 691 $768,744,621 Urology Explore This Profile
18. Massachusetts General Physicians Organization 550418 2,387 $751,873,640 Internal Medicine Explore This Profile
19. University of Penn Medical Group 697339 2,318 $737,669,858 Internal Medicine Explore This Profile
20. Sunrise Health Physicians 1001654 659 $715,044,923 Obstetrics/Gynecology Explore This Profile
21. El Camino Hospital Physicians 995192 1,318 $705,123,248 Internal Medicine Explore This Profile
22. Stanford Hospitals and Clinics 706374 2,129 $687,719,791 Anesthesiology Explore This Profile
23. Duke Health Providers 630957 2,031 $676,263,171 Internal Medicine Explore This Profile
24. Christiana Care Health Services 759255 1,336 $674,028,812 Internal Medicine Explore This Profile
25. Northwestern Medical Group 552709 1,395 $641,537,600 Internal Medicine Explore This Profile

Fig 2. Data from Definitive Healthcare based on the most recent CMS Physicians Compare File as of August 2019