IRT may refer to:
Iranian toman, Currency used in Iran
Immunoreactive trypsinogen, used as a newborn screening test for cystic fibrosis
Indiana Repertory Theatre, a theatre in Indianapolis, Indiana
Infrared thermography
Infrared triplet of Ca II
Institut für Rundfunktechnik, the research institute of the public broadcasters of Germany, Austria, and Switzerland
Interborough Rapid Transit Company, former operator of a portion of the New York City Subway system
Isochronous real time, a computer protocol used for PROFINET IO
Interactive Response Technology, used e.g. in planning of drug supply during clinical trials
Item response theory, a theory to interpret data from psychometric tests
Ice Road Truckers, a documentary television series on History Channel