The present study aimed to investigate the perception of risk in the Brazilian population related to electric and magnetic fields. Six hundred adults were recruited from the surrounding communities. Three hundred of them lived in large cities and an equal number lived in small towns. A short questionnaire was constructed to assess risk perception, trust in government to control risk exposure, level of comfort with exposure to extra-low-frequency electromagnetic fields, measures perceived as necessary to reduce emotional discomfort, and trust in the regulatory agencies. The Lipp Inventory of Stress Symptoms for Adults was applied to assess stress levels. Findings indicate that the majority of the participants in this study did not trust the Government to provide protective measures from exposure to electric and magnetic fields, did not trust the regulatory agencies, felt that there is no adequate risk control and thought about it frequently, and some felt that line installations were being performed in excess and that this should be stopped. Results endorse the need for risk education and indicate that risk perception and feelings should be considered before starting new line installations. Risk communication should incorporate knowledge regarding social cognition since a large proportion of the people were concerned about electric and magnetic fields. Lack of communication can lead to a rejection of necessary transmission line installation, and to unnecessary or exaggerated fear.