Several studies on epidemiology of epilepsy were carried out in different parts of the world. However, the majority of their data was collected from hospitals, clinics, individual physicians and or small communities. Although these studies have contributed to our knowledge as to the risk factors of epilepsy, some of them have prevented us from further generalization, since the prevalence rates of the phenomena were not known for the entire population where from they were derived. Latin America has remained without epidemiological data, specialy prevalence rates, for many years. A house-to-house survey was programmed by the Brazilian League of Epilepsy in the urban area of S. Paulo City the third largest cosmopolitan city in the world: 13 million inhabitants in 1980. A significant sample of 2011 houses was chosen by statistical means. A total of 7603 interviews were performed by 50 senior medical students and nurses, and 388 persons were considered suspect and further referred to our University Hospital for other studies; 348 of these were examined, and in 91 the diagnosis of epilepsy was confirmed, thus producing a prevalence rate 11,9 per 1000.