We investigated the EEG frequency distribution by quantitative EEG (QEEG) in 28 children with type 1 diabetes and 28 age- and sex-matched control children. Among the diabetic children, 15 had experienced episodes of severe hypoglycemia (SH group) and 13 had not experienced such episodes (non-SH group). The EEG analysis was blind. Frequency analysis of 15 EEG epochs, each of 4 s duration, was performed. QEEG showed increased theta activity in the SH group bilaterally in the frontocentral region and a slight trend toward more delta activity in diabetic children than control children bilaterally in the occipital electrodes. The relative alpha amplitude was decreased in the SH group at several locations. Abnormal standard EEG (diffuse theta activity) was observed in two SH patients and one non-SH patient. All control children had normal standard EEG. We conclude that episodes of severe hypoglycemia may affect frontocentral function slightly in some diabetic children.