Epileptiform discharges in 8 electrode waking EEGs at rest and during hyperventilation in 1,057 healthy children aged 6-12 years from an elementary school were studied: Epileptiform discharges, detected in 53 children (5.0%), consisted of centrotemporal spikes (37 cases), generalized spike and slow wave complexes (10 cases), occipital spikes (2 cases), frontal spikes (1 case), and a combination of multiple spike and slow wave complexes and focal spikes (2 cases). The occurrence of a positive past history of febrile convulsions was higher in children with epileptiform discharges (18.9%) than in those without epileptiform discharges (9.4%). Using the Rutter scales for teachers and parents, we compared the emotional and behavioral problems of children with epileptiform EEG discharges with those of children without epileptiform discharges. No statistically significant differences were noted, indicating that the emotional and behavioral problems existing are most probably coincidental and not directly related to the epileptiform discharges. A genetic basis for generalized epileptiform discharges was postulated because the occurrence of generalized discharges in siblings of probands with generalized discharges was higher (4 of 9, 44.4%) than the prevalence in all subjects. However, the occurrence of centrotemporal spikes in the siblings of probands with centrotemporal spikes was not higher (2/38, 5.3%) and an autosomal-dominant genetic factor for centrotemporal spikes in waking EEGs of healthy children could not be confirmed.