To investigate an association between surface electrocardiographic (ECG) parameters and sustained ventricular tachycardia (VT) in children after repair of congenital heart disease (CHD), data were obtained and analyzed in three groups (group I, 7 postoperative patients with episode of sustained VT (4 tetralogy of Fallot (TOF), 2 double outlet right ventricle (DORV), 1 truncus arteriosus); group II, 14 children with postoperative TOF not associated with VT; group III, 14 normal children). Mean age at the onset of sustained VT was 129±77 months (range 60-232); mean age at corrective surgery, 44±33 months (range 10-102); mean follow-up period after surgery, 84±74 months (range 20-185); the duration from repair to the onset of sustained VT, range 1-185 months. Compared to group II and III, group I showed longer QRS duration (group I, 137±10 msec; group II, 114±22 msec; group III, 65±12 msec) and shorter corrected J to T_max interval (group I, 209±24 msec; group II, 272±44 msec; group III, 249±18 msec). QT and corrected QT, J to T_max interval, and their dispersions in group I and II are significantly different from those of group III. In conclusion, QRS duration and corrected J to T_max interval could be helpful to predict ventricular tachycardia in postoperative CHD.