IRT or irt may refer to:
Organizations
Indiana Repertory Theatre, an American company of actors Institut für Rundfunktechnik, a German research institute for broadcasters Interborough Rapid Transit Company, a defunct New York subway operator
Science and technology Imagery Rehearsal Therapy, see Immunoreactive trypsinogen, newborn screening test for cystic fibrosis Infrared thermography Infrared Telescope, on the STS-51-F Space Shuttle mission Item response theory, to interpret psychometric tests
Television Ice Road Truckers, a reality television series International Response Team, a fictional body in Criminal Minds
Other uses IR Tanger, a Moroccan association football club Incident response team, a group of people who respond to an emergency International Registry of Tartans, a Scottish Tartans Authority textile database