IEM can refer to:

• I.E.M. (album)
• Inborn error of metabolism
• In-ear monitors, devices used by musicians, audio engineers and audiophiles to listen to music
• Incredible Expanding Mindfuck (Music)
• Information Engineering Methodology
• Innovative Emergency Management
• Institute of Electronic Music and Acoustics (Institut für Elektronische Musik und Akustik), part of the University of Music and Performing Arts, Graz
• Institute of Engineering and Management
• Integrated Enterprise Modeling
• Institute of Engineering in Medicine, part of the University of California, San Diego
• Institute for Experimental Mathematics, a central scientific facility of the University of Duisburg-Essen
• Intel Extreme Masters, a series of international esports tournaments
• International emergency medicine
• Internet Explorer Mobile
• Ion evaporation model, a model explaining electrospray ionization in mass spectrometry
• Iowa Electronic Markets
• Internal Energy Market, of the European Union