IEI

IEI may mean:
 * Inborn errors of immunity, genetic mutations that cause an increased susceptibility to disease
 * Idiopathic environmental intolerance, also known as multiple chemical sensitivity
 * Institute for Emerging Issues
 * Institution of Engineers (India)
 * Institut d'échanges interculturels
 * Institution of Engineers of Ireland
 * Intensive English Institute, at the University of Illinois Urbana-Champaign
 * Intuitive Ethical Introvert, in socionics theory
 * Iran Electronics Industries