Myocardial transmural dispersion of repolarization (TDR) has been associated with reentrant arrhythmias in animal studies but a clinical association has not yet to been demonstrated. The present study examines the relationship between TDR and ventricular tachyarrhythmias in human subjects. This study consisted of 65 patients with non-sustained ventricular tachycardia, sustained ventricular tachycardia, ventricular fibrillation or unexplained syncope with organic heart disease. The control group included 65 patients with paroxysmal supraventricular tachycardia. The 12 ECG was recorded at a recording rate of 100 mm/sec. The interval from the peak to the end of the T wave in the precordial (ECG), referred to as TpTe was assumed to be representative of TDR. Patients were divided into three groups based on the ability to induce VT at the time of electrophysiologic study: VT inducible group (n=37), VT non-inducible group (n=25) and control group (n=65). V4 TpTe/ radical RR was significantly prolonged in the VT inducible group, as compared to the VT non-inducible group (n=25) and the control group (118.9 +/- 26.1 vs. 103.9 +/- 25.7, 104.1 +/- 22.6 ms, P<.05). Patients who develop VT spontaneously (n=13) during a mean follow-up period of 25 months, displayed significantly prolonged V3 TpTe/ radical RR, compared to patients who did not develop VT spontaneously or the control group (132.5 +/- 37.4 vs. 109.8 +/- 26.3, 107.1 +/- 24.1 ms, P <.05). Prolonged TDR is associated with inducibility as well as spontaneous development of VT in higher risk patients. TDR may be a useful index for predicting ventricular tachyarrhythmias.