| OPTA | Oak Park Tennis Association 
| Others |
| OPTA | Ohio Physical Therapy Association
| Others |
| OPTA | Ohio Public Transit Association
| Others |
| OPTA | Oklahoma Physical Therapy Association
| Others |
| OPTA | Old Pueblo Touring Association
| Others |
| OPTA | Onafhankelijke Post en Telecommunicatie Autoriteit
| Others |
| OPTA | Ontario Public Transit Association
| Others |
| OPTA | Optimum Performance Theoretically Attainable
| Others |
| OPTA | Oregon Permit Technicians Association
| Others |
| OPTA | Oregon Physical Therapy Association
| Others |
| OPTA | Oregon Pupil Transportation Association
| Others |
| OPTA | Organic Producers Trade Association
| Others |
| OPTA | Orthopaedic Physical Therapy Associates
| Others |
| OPTA | Orthotic Prosthetic Technological Association
| Others |