• Rape Trauma Syndrome
• Real-time strategy, a gaming genre
• Reclaim the Streets, an anarchist organization
• Reformed Theological Seminary, a theological seminary in the United States
• Return to Sender
• Ronald Reagan Ballistic Missile Defense Test Site, also known as the "Reagan Test Site"
• Rett syndrome

In economics:

• Returns to scale, an economics concept
• Russian Trading System, a stock exchange in Russia

In transportation:

• Rapid Transit Series, a long running bus model originally manufactured by General Motors Corporation
• Regional Transit Service, a division of the Rochester-Genesee Regional Transportation Authority
• Regional Transit System, a bus system serving Gainesville, Florida and the University of Florida

In radio and television:

• Royal Television Society, a UK-based society for the discussion of television
• Radiodiffusion Télévision Sénégalaise, the Senegalese national broadcasting company
• Radio Television of Serbia, the national broadcasting company of Serbia
• Radio & Television of Singapore, a former name of MediaCorp Singapore
• RTS, the callsign of a TV station in Loxton, South Australia

In technology:

• Ready-To-Serve, provide services to end users.
• Return statement or ReTurn from Subroutine, a statement in many assembly languages and other low-level computer languages
• Run-time system, a part of some computer's runtime environment
• Radio teleswitch service, which regulates energy rates via broadcast radio in the UK
• SIGRTMIN and SIGRTMAX or Real-time signal, signals sent to computer programs for user-defined purposes
• A "Request to Send" frame in the IEEE 802.11 RTS/CTS mechanism
• A "Request to Send" signal in RS-232 communications