RCS may refer to:
- Clubs and societies
- Racing Club de Strasbourg
- Radcliffe Choral Society
- Royal College of Science
- Royal College of Surgeons
- Royal Commonwealth Society
- Technology
- Radar cross-section
- Radio Computing Services
- Reaction control system
- Real-time Control System
- Computing
- Resource construction set
- Return channel via satellite
- Revision Control System
- Rich Communication Suite
- Other
- Republika Československá (Republic of Czechoslovakia), Czechoslovakia's official name between 1918 and 1920
- Representation of Czechs and Slovaks, name of the Czechoslovakian football team after the breakup of the country but before the breakup of the team
- Rochester Airport, England, the IATA airport code
- Riverdale Country School, Bronx, NY
- Rizzoli-Corriere della Sera, aka RCS Mediagroup, an Italian publishing group
- Romania Cable Systems
- Royal Conservatoire of Scotland
- Rural Clinical School of Western Australia
- Recombinant congenic strain
- Rectangular coordinate system, usually known as Cartesian coordinate system
- Red cherry shrimp, a shrimp often kept in aquariums