Electromagnetic (EM) fields are generated by several natural and man-made sources. Part of the electromagnetic spectrum called Radiofrequency (RF; 10 kHz -300 GHz) is used in communications, mobile phones, radio and television broadcasts, etc. Extremely Low Frequency (ELF; 0 -300 Hz) region of the spectrum is radiated by transformers, high power lines, household or working area appliances, and by the electrical goods. The use of electromagnetic waves increases due to the technological improvements, therefore, people are exposed to high levels of electromagnetic fields in their daily lives. The health priority of public concerns occurred about the mobile phones, base stations and wireless technologies. Furthermore, the sensitivity of the public is increasing on their adverse effects on the human health. The biological and health effects of EM radiation have been investigated for more than 25 years in Biophysics Department at Gazi University. In this study, the sources and the effects of EM fields along with the studies performed in Gazi Biophysics are summarized, and Gazi Non-Ionizing Radiation Protection Center (GNRK), the first scientific center founded to measure EM fields, is introduced. (Archives of Neuropsychiatry 2010; 47: 158-61)