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
Romsdalshalvøya Interkommunale Renovasjonsselskap, a Norwegian waste management agency
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