The authors studied the EEG of 20 children with history of a single epileptic seizure, in order to establish a presumptive pathological factor in the central nervous system. In this series, 13 patients (65%) had abnormal tracings, and 7 (35%) had normal EEG records. The most frequent abnormality found was a focal change, recorded in 12 patients, while the diffuse type was found in just one. Abnormal tracings, either at rest or during overventilation, were most frequently seen in 8 patients which had recurrent seizures, registered in a three years follow-up.