RPSI
| Acronym | Definition |
|---|---|
| RPSI | Rheinland Pfalz Saar International (horse breed) |
| RPSI | Railway Preservation Society of Ireland |
| RPSI | Relative Penis Size Index |
| RPSI | Reliable Power Systems, Inc. (Castle Rock, CO) |
| RPSI | Rapid Prototyping Society of India (est. 2001) |
| RPSI | Retriever Payment Systems, Inc. (Houston, TX) |