RIR may refer to:
- Regional Internet registry, nonprofit corporations that administer and register Internet Protocol (IP) address space and Autonomous Systems (AS)
Companies and organizations
- Richmond International Raceway
- Riverside International Raceway
- British Army regiments:
- Royal Irish Rangers
- Royal Irish Rifles
- Royal Irish Regiment, either:
- Royal Irish Regiment (1684–1922)
- Royal Irish Regiment (1992)
Media and entertainment
- Real Illusions: Reflections, an album by American guitarist Steve Vai
- Rock in Rio, a recurring music festival, originating in Rio de Janeiro, Brazil
- Rush in Rio, a live album by Canadian band Rush
Political parties
- React-Include-Recycle, a political party of Portugal
Other uses
- Rhode Island Red, a breed of chicken