IET can refer to:

• Institute of Educational Technology, part of the Open University
• Institution of Engineering and Technology, a UK-based professional engineering institution
  • Institute of Engineers and Technicians, which became part of the Institution of Incorporated Engineers in 1998 (which then became part of the Institution of Engineering and Technology in 2006)
• Institute of Engineering and Technology of Lucknow, India
• University Institute of Engineering and Technology, Kanpur University of Kanpur, India, formerly known as IET Kanpur
• Institute of Engineering Technology, Sri Lanka, a Government higher education institute that providing NDES (National Diploma in Engineering Sciences) Award in Sri Lanka
• IET Bhaddal, an engineering institute based in Bhaddal, Punjab
• Islamic Educational Trust, Islamic organization in Nigeria
• Institute of Engineering and Technology, Ayodhya of Faizabad, Uttar Pradesh, India

• iET (musician), a singer-songwriter from the Netherlands

• Impulse excitation technique
• Initial Entry Training, the technical term for United States Army Basic Training
• Interval exchange transformation
• Interest Equalization Tax, an American tax initiative

• British Rail Class 800, a fleet of British high-speed trains, known as Intercity Express Trains by their operator Great Western Railway
• British Rail Class 802, another fleet of British high-speed trains, known as Intercity Express Trains by their operator Great Western Railway
• Indole-3-ethanol or tryptophol, a chemical compound