| Mission Community Hospital | Panorama City, CA | Acute Care Hospitals | 3 stars |
| Mission Regional Medical Center | Mission, TX | Acute Care Hospitals | 4 stars |
| Mississippi Baptist Medical Center | Jackson, MS | Acute Care Hospitals | 2 stars |
| Mississippi Methodist Rehab Ctr | Jackson, MS | Acute Care Hospitals | Not rated |
| Missouri Baptist Medical Center | Saint Louis, MO | Acute Care Hospitals | 5 stars |
| Missouri Baptist Sullivan Hospital | Sullivan, MO | Critical Access Hospitals | 2 stars |
| Missouri Delta Medical Center | Sikeston, MO | Acute Care Hospitals | 2 stars |
| Mizell Memorial Hospital | Opp, AL | Acute Care Hospitals | 1 star |
| Moab Regional Hospital | Moab, UT | Critical Access Hospitals | Not rated |
| Mobile Infirmary Medical Center | Mobile, AL | Acute Care Hospitals | 2 stars |
| Mobridge Regional Hospital - CAH | Mobridge, SD | Critical Access Hospitals | Not rated |
| Molokai General Hospital | Kaunakakai, HI | Critical Access Hospitals | Not rated |
| Mon Health Marion | Whitehall, WV | Acute Care Hospitals | Not rated |
| Mon Health Medical Center | Morgantown, WV | Acute Care Hospitals | 4 stars |
| Monadnock Community Hospital | Peterborough, NH | Critical Access Hospitals | 2 stars |
| Monmouth Medical Center | Long Branch, NJ | Acute Care Hospitals | 3 stars |
| Monmouth Medical Center-Southern Campus | Lakewood, NJ | Acute Care Hospitals | 3 stars |
| Monroe Regional Hospital | Aberdeen, MS | Critical Access Hospitals | Not rated |
| Montclair Hospital Medical Center | Montclair, CA | Acute Care Hospitals | 3 stars |
| Montefiore Medical Center | Bronx, NY | Acute Care Hospitals | 3 stars |
| Montefiore Mount Vernon Hospital | Mount Vernon, NY | Acute Care Hospitals | 3 stars |
| Montefiore New Rochelle Hospital | New Rochelle, NY | Acute Care Hospitals | 1 star |
| Montefiore St Luke's Cornwall | Newburgh, NY | Acute Care Hospitals | 2 stars |
| Montgomery County Emergency Service | Norristown, PA | Psychiatric | Not rated |
| Montrose Regional Health | Montrose, CO | Acute Care Hospitals | 4 stars |
| Monument Health Custer Hospital | Custer, SD | Critical Access Hospitals | Not rated |
| Monument Health Lead-Deadwood Hospital | Deadwood, SD | Critical Access Hospitals | Not rated |
| Monument Health Rapid City Hospital | Rapid City, SD | Acute Care Hospitals | 3 stars |
| Monument Health Spearfish Hospital | Spearfish, SD | Acute Care Hospitals | 4 stars |
| Morgan County ARH Hospital | West Liberty, KY | Critical Access Hospitals | Not rated |
| Morris Hospital & Healthcare Centers | Morris, IL | Acute Care Hospitals | 4 stars |
| Morristown Medical Center | Morristown, NJ | Acute Care Hospitals | 5 stars |
| Morton Plant Hospital | Clearwater, FL | Acute Care Hospitals | 4 stars |
| Morton Plant North Bay Hospital | New Port Richey, FL | Acute Care Hospitals | 3 stars |
| Mosaic Life Care at St Joseph | Saint Joseph, MO | Acute Care Hospitals | 4 stars |
| Mosaic Medical Center - Maryville | Maryville, MO | Critical Access Hospitals | Not rated |
| Mosaic Medical Center Albany | Albany, MO | Critical Access Hospitals | Not rated |
| Moses H. Cone Memorial Hospital, the | Greensboro, NC | Acute Care Hospitals | 3 stars |
| Mount Auburn Hospital | Cambridge, MA | Acute Care Hospitals | 4 stars |
| Mount Carmel East & West | Columbus, OH | Acute Care Hospitals | 2 stars |
| Mount Carmel St Ann's | Westerville, OH | Acute Care Hospitals | 3 stars |
| Mount Desert Island Hospital | Bar Harbor, ME | Critical Access Hospitals | Not rated |
| Mount Nittany Medical Center | State College, PA | Acute Care Hospitals | 5 stars |
| Mount Pleasant Hospital | Mount Pleasant, SC | Acute Care Hospitals | 5 stars |
| Mount Sinai Beth Israel | New York, NY | Acute Care Hospitals | 3 stars |
| Mount Sinai Hospital | New York, NY | Acute Care Hospitals | 4 stars |
| Mount Sinai Medical Center of Florida, Inc | Miami Beach, FL | Acute Care Hospitals | 3 stars |
| Mount Sinai South Nassau | Oceanside, NY | Acute Care Hospitals | 3 stars |
| Mount St. Mary's Hospital & Health Center | Lewiston, NY | Acute Care Hospitals | 2 stars |
| Mount Washington Pediatric Hospital | Baltimore, MD | Childrens | Not rated |