- Mercy Health (MO)
- Mercy Health (Ohio)
- Mercy Health (WI)
- Mercy Medical Center
- MercyOne
- Meridian Health Services
- Merit Health
- Meritus Health
- Methodist Health System
- Methodist Hospitals
- Methodist Le Bonheur Healthcare
- Metro Pavia Health System
- MetroWest Medical Center
- Michigan Department of Health & Human Services
- MidCoast Health System
- Middlesex Health System
- Midland Memorial Health
- Mills-Peninsula Medical Center
- Minnesota Department of Human Services
- Minnie Hamilton Health System
- Mission Health System
- Mississippi County Hospital System
- Mississippi Department of Mental Health
- Missouri Department of Mental Health
- Moffitt Cancer Center
- Mohawk Valley Health System
- Mon Health
- Montefiore Medical Center
- Montrose Behavioral Health Hospital
- Monument Health