From 1971 to 1978, 5,202 schoolchildren from the first to the 9th grade underwent mass screening EEG. Paroxysmal discharges were recognized in 1.7%. Focal paroxysmal discharges appeared most frequently and the temporal, occipital, and central areas were the most common sites. Children having autonomic seizures, psychomotor seizures, and absence seizures do exist among allegedly healthy children without being noticed. For the early detection of these, mass screening EEG was very useful. Abnormal EEGs, particularly abnormal basic activities were often found in epileptic children, but had no definite correlation with behavior disorders or with scholastic achievements. According to the mass screening EEG in 1978 involving 1,921 children from the first to the 6th grades of primary school, 2.5% had suspected epileptic seizures, and 7.9% had histories of febrile convulsions.