MIR can refer to:
- MIR (submersible) Soviet and Russian bathyscaphes
- Habib Bourguiba International Airport in Tunisia
- Mail-in rebate
- Medical Inspection Room, the place for sick parade in most British and Commonwealth militaries and many Non-governmental organizations
- Metropolitan Intercity Railway Company, a Japanese company operating the Tsukuba Express, from Akihabara Station to Tsukuba Station
- Micropower Impulse Radar, a compact low-power radar system developed at Lawrence Livermore National Laboratory
- Mid(-wavelength) Infrared Radiation, see Infrared
- Mid-level intermediate representation, one of intermediate representations of a computer program in compiler
- Minneapolis Industrial Railway (AAR reporting marks MIR)
- Maximum Information Rate, in Radios the maximum bandwidth the Subscriber Unit will be delivered from the Access Point in kbit/s
- Movimiento de Izquierda Revolucionaria, the name of several political parties in Latin America.
- Music Information Retrieval
- Moving Image Retoucher (M.I.R.)
- Multiple isomorphous replacement, a technique used in crystallography
