In recent years there has been an increased interest in biological effects of magnetic fields. Both, beneficial applications and potential hazards due to exposure to static and time-varying magnetic fields have been considered. In this context it is important to know levels of human exposure to these fields in occupational and everyday situations. In this paper human exposures to magnetic fields in various areas of human activity are reviewed: high-energy technologies, induction heating, medical imaging, electricity distribution and others. Fields of frequencies from zero to a few hundred kilohertz are included.