- Outdoor swimming pool
- Organic drug store
- Ophthalmologist
- Orthopedic surgeon
- Oil refinery
- Occupational medical physician
- Oil wholesaler
- Occupational safety and health
- Orthopedic clinic
- Occupational health service
- Osteopath
- Optician
- Orthopedic shoe store
- Optometrist
- Orthotics & prosthetics service
- Otolaryngologist
- Oil store
- Orthoptist
- Outdoor bath
- Occupational therapist