IAR may refer to:

• IAR Systems, an embedded system technology company
• The Institute of Audio Research
• The Institute of Asian Research, an institute under the Faculty of Arts in the University of British Columbia, Vancouver, BC, Canada
• "Ignore all rules", a policy on Wikipedia
• Industria Aeronautică Română (IAR Braşov), an aerospace manufacturer
• M27 Infantry Automatic Rifle, the primary service rifle/automatic rifle issued to U.S. Marine Corps infantry units
• Institute of Advanced Research, a private university in Gujarat, India
• Instruction address register, an alternative name for the program counter CPU register
• International Authority for the Ruhr, an organization in control of the industry in the Ruhr area from 1949 to 1952
• International Affairs Review, an academic journal in the field of international affairs
• Informacyjna Agencja Radiowa, a Polish news agency
• The IATA code for the Tunoshna Airport, Yaroslavl Oblast, Russia
• .iar, Inventory ARchive file used for avatar inventory backup in OpenSimulator virtual environments
• Investment Adviser Representative employed by a registered investment adviser, a firm that is an investment adviser in the United States