Electrocardiographic characteristics evaluated by body surface mapping were investigated, comparing with the other clinical findings. Isopotential maps were abnormal at the end of QRS period when the positive area persisted in the anterior middle and lower chest. VAT was also prolonged in these area. Post excitation (Epsilon) waves appeared at that period in accordance with the rapid potential change on upper anterior chest which reflected right ventricular conduction delay. There was no difference in electrophysiologic findings in patients with or without Epsilon waves. Negative potentials were present on the anterior chest in ST-T isopotential, ST-T and QRST isointegral maps in all of the patients. The area of these negative potentials was closely correlated with RV dilatation and dysfunction. It is concluded that Epsilon waves are not the direct counterpart of delayed potentials, but the reflection of the peripheral induction delay, and that primary change seems to play large part of the genesis in negative T waves.