A prospective study of 3 years' duration on the etiology of late onset epilepsy was carried out in a rural health area with a population of 135,000. Eighty patients were included. History, neurological physical examination, electroencephalogram, cranial computed tomographic scan (CT) and general laboratory investigations were carried out. The cause of epilepsy was unknown in 51.3% of cases. The most commonly identified causes were cerebrovascular disease (20%), chronic alcohol abuse (10%), tumors of central nervous system (6.3%), neurocysticercosis (6.3%) and post-traumatic epilepsy (2.5%). Our data are compared with those from the previous literature, and the value of cranial CT in the investigation of this clinical condition is discussed.