- Others
- Orthopedic clinic
- Otolaryngologist
- Ophthalmologist
- Oral and maxillofacial surgeon
- Oncologist
- Occupational safety and health
- Osteopath
- Oral surgeon
- Orthodontist
- Orphanage
- Obstetrician-gynecologist
- Orthopedic surgeon
- Orthopedic shoe store
- Office furniture store
- Outdoor furniture store
- Office supply store
- Organic drug store
- Organic food store
- Orthoptist