IRM

IRM may refer to:
 * IERS Reference Meridian
 * Illinois Railway Museum
 * Illinois Reserve Militia, state defense force active during World War II
 * Bureau of Information Resource Management, responsible for information technology of the U.S. Department of State
 * Information Rights Management
 * Intermediate Restorative Material (Dentistry) Zinc oxide eugenol
 * L'Institut Royal Météorologique de Belgique
 * Interference reflection microscopy, a microscopy method used to image adherent cells
 * Internal Revenue Manual, an official compendium of internal guidelines for personnel of the United States Internal Revenue Service
 * International Review of Mission, a quarterly academic journal
 * International Roaming MIN assigned by IFAST
 * IRM (album), by Charlotte Gainsbourg
 * Iron Mountain Incorporated, a data storage company based in Boston, Massachusetts
 * ICAO designator for Mahan Air, an Iranian airline
 * Islamic Republic of Mauritania
 * Irish Republican Movement