IGR may refer to:
- Iguazu International Airport serving Puerto Iguazú and the nearby falls
- IGR Iwate Ginga Railway in Iwate Prefecture, Japan
- Imperial Japanese Government Railways (or, domestically, Imperial Government Railways) of early 20th century Japan
- Indiana Guard Reserve
- Insect growth regulator, a chemical that disrupts the growth and/or development of insects
- The Interessengemeinschaft für Rundfunkschutzrechte (IGR), a broadcasting "IP" rights interest group
- IGR Stereo, a German standard for analogue TV stereo audio transmission claimed by the above organization.
- Intergenic region
- Inscriptiones Graecae ad res Romanas pertinentes, a four-volume selection of Ancient Greek inscriptions from Roman times edited by French historian René Cagnat.