RDOS may refer to:

• Regional District of Okanagan-Similkameen, a regional district of British Columbia
• Data General RDOS, a real-time operating system by Data General since 1972
• Cromemco RDOS, the resident operating system on some Cromemco S-100 cards
• RDOS (Microsoft), a name sometimes used for the Russian versions of MS-DOS 4.01 and 5.00
• RDOS (Ekblad), a 32-bit DOS-compatible operating system by Leif Ekblad since 1988

• DOS (disambiguation)
• ROS (disambiguation)
• RTOS, real-time operating system
• REAL/32