| Massachusetts General Physicians Organization Inc | Boston | 3,558 |
| Brigham and Womens Physicians Organization Inc | Boston | 2,994 |
| Umass Memorial Medical Group Inc | Worcester | 2,516 |
| Harvard Medical Faculty Phys at Beth Israel Deaconess Med Ctr Inc | Boston | 1,740 |
| Lahey Clinic Inc | Burlington | 1,381 |
| Baystate Medical Practices Inc | Springfield | 1,369 |
| The General Hospital Corporation | Boston | 1,267 |
| Atrius Health Inc | Braintree | 1,222 |
| Southcoast Physicians Group Inc | New Bedford | 881 |
| Mass General Brigham Medical Group Northern Massachusetts Inc | Danvers | 827 |
| Dana-Farber Cancer Institute, Inc. | Boston | 684 |
| Cambridge Public Health Commission | Everett | 656 |
| Reliant Medical Group Inc | Worcesteer | 640 |
| Mass General Brigham Medical Group Suburban Massachusetts Inc | Pembroke | 602 |
| Associated Physicians of Harvard Medical Faculty Physicians at Beth Is | Milton | 565 |
| Bmc Affiliated Physicians, Inc. | Brockton | 564 |
| Evans Medical Foundation Inc | Boston | 536 |
| Northeast Health Services LLC | Framingham | 479 |
| Lifespan Physician Group of Massachusetts Inc | Fall River | 476 |
| Bay State Physical Therapy of Randolph Inc | Halifax | 454 |
| Coastal Medical Associates | Weymouth | 443 |
| Massachusetts Eye and Ear Associates, Inc | Boston | 433 |
| Mass General Brigham Community Physicians Inc | Watertown | 428 |
| Beth Israel Lahey Health Primary Care, Inc | South Hamilton | 353 |
| Physicians of Cape Cod Hospital | Hyannis | 334 |
| Children's Hospital Pediatric Associates, Inc | Boston | 328 |
| Silver Fern Practice LLC | Attleboro | 298 |
| Medical Care of Boston Management Corporation | Dedham | 292 |
| Mass General Brigham Medical Group Western Massachusetts Inc | Northampton | 291 |
| Northeast Orthopaedic Alliance PLLC | Dedham | 291 |
| Pratt Medical Group Inc | Boston | 286 |
| Child and Family Psychological Services PLLC | Canton | 278 |
| Berkshire Faculty Services Inc | Pittsfield | 276 |
| Beth Israel Lahey Health Specialty Care, Inc. | Burlington | 267 |
| Signature Healthcare Medical Group Inc | Brockton | 247 |
| Internal Medical Associates-Ebnhc | East Boston | 240 |
| Emerson Practice Associates, Inc | Concord | 240 |
| Mount Auburn Professional Services Inc | Cambridge | 231 |
| Medical Affiliates of Cape Cod Inc | Hyannis | 229 |
| Riverbend Medical Group Inc | Agawam | 226 |
| Prima Care, PC | Fall River | 220 |
| Milford Regional Physician Group, Inc. | Milford | 210 |
| Holyoke Medical Center Inc | Holyoke | 205 |
| Performance Rehabilitation of Western New England LLC | Boston | 205 |
| Berkshire Medical Center Inc | Pittsfield | 203 |
| University Orthopedics Inc | Mansfield | 196 |
| The McLean Hospital Corporation | Belmont | 192 |
| Sturdy Health Inc | Mansfield | 189 |
| South Shore Medical Center, Inc. | Norwell | 175 |
| Jordan Physician Associates Inc | Plymouth | 167 |
| Lgh Medical Group, Inc. | Lowell | 166 |
| Proex Physical Therapy LLC | Winchester | 165 |
| Community Medical Associates, Inc. | Haverhill | 157 |
| Pratt Anesthesiology Associates Inc | Boston | 155 |
| Martha's Vineyard Hospital Inc | Oak Bluffs | 155 |
| Behavioral Health Network Inc | Springfield | 150 |
| National Health Rehabilitation LLC | Natick | 149 |
| Hallmark Health Medical Associates Inc | Melrose | 147 |
| The Commonwealth of Massachusetts | Boston | 146 |
| Harbor Medical Associates Inc | Pembroke | 127 |
| Beth Israel Deaconess Medical Center Inc | Boston | 127 |
| Chmc Anesthesia Foundation Inc | Boston | 126 |
| Lawrence Anesthesia Services LLC | Worcester | 125 |
| Lawrence General Hospital | Lawrence | 123 |
| Greater Lawrence Family Health Center Inc | Lawrence | 122 |
| Charles River Medical Associates, PC | Hudson | 119 |
| Riverside Community Care Inc | Somerville | 117 |
| Henry Heywood Memorial Hospital | Gardner | 115 |
| Jefferson Radiology PC | Needham | 114 |
| Advocates, Inc. | Framingham | 112 |
| Revere Medical of Massachusetts PC | Norwood | 111 |
| Minuteclinic Diagnostic of Massachusetts, LLC | Medford | 110 |
| Heywood Medical Group Inc. | Gardner | 110 |
| Valley Medical Group PC | Easthampton | 108 |
| Boston University Psychiatry Associates, Inc. | Boston | 106 |
| Hri Clinics, Inc. | Haverhill | 103 |
| Mass General Brigham Urgent Care LLC | Brookline | 102 |
| Lowell Anesthesiology Service Inc | Lowell | 101 |
| Clinical and Support Options, Inc | Northampton | 100 |
| Boston Childrens Heart Foundation Inc | Boston | 100 |
| Supportive Behavioral Care of Ma LLC | Boston | 99 |
| President and Fellows of Harvard College | Cambridge | 97 |
| Cardiovascular Center at Tufts Medical Center Inc | Boston | 97 |
| Lynn Community Health, Inc. | Lynn | 95 |
| Boston University Medical Center Anesthesiologists Inc | Boston | 93 |
| Family Health Center of Worcester, Inc. | Worcester | 92 |
| Physicians of Falmouth Hospital | Falmouth | 92 |
| Commonwealth Anesthesia Associates, Inc | Newton | 92 |
| Community Health Connections, Inc | Fitchburg | 91 |
| Connections Physical Therapy, Inc. | Wellesley | 89 |
| Curana Health of Massachusetts LLC | Weymouth | 88 |
| Healthdrive Behavioral Health Services, PLLC | Framingham | 88 |
| Ch Specialty Services Ma PC | Springfield | 88 |
| Sports Medicine North Orthopaedic Surgery, Inc. | Peabody | 87 |
| Nantucket Cottage Hospital | Nantucket | 87 |
| Lowell Community Health Center, Inc. | Lowell | 86 |
| Northeast Dermatology Associates PC | North Falmouth | 85 |
| Hospitalist Physicians of Massachusetts PC | Worcester | 85 |
| Moonshot Psychiatric Nurse Practitioner PC | Boston | 84 |
| Boston University General Surgical Associates, Inc. | Boston | 84 |