- Office of the Actuary
- Office of the Actuary at the Centers for Medicare & Medicaid Services
- Ohana Pacific Health
- Ohio Health Care Association
- Ohio Living
- Ohio Long-Term Care Research Project
- Ohio Senior Living
- Ohio's Hospice
- Ohman Family Living
- OIG
- Oklahoma Health Care Authority
- Oklahoma State Department of Health
- Olio
- Olio Health
- Oliver Wyman
- OMB
- Omega
- Omega Health Care Investors
- Omega Healthcare Investors
- Omega Senior Living