Background: Idiopathic ventricular fibrillation and/or sudden death may occur in some patients with ST-segment elevation in right precordial leads. The mechanism of such events has been explained as a pure electrical disease. However, underlying cardiomyopathies such as arrhythmogenic right ventricular cardiomyopathy (ARVC) and wall motion abnormalities were reported in some patients with ST-segment elevation in right precordial leads. Therefore, we sought to assess whether the morphological or pathological abnormalities underlies in these patients. Methods and results: Thirteen consecutive male patients aged 4410 years with ST-segment elevation more than 2 mm in right precordial leads underwent cardiac evaluation, including 12-leads ECG, echocardiography, electrophysiology, ventriculography and endomyocardial biopsy. We also evaluated coronary angiography with induction of coronary artery spasm test, and examined the augmentation of ST-segment elevation in the right precordial leads by injection of sodium channel blockers. Eight patients had coved type ST-segment elevation (type 1) and five patients had saddle-back type ST-segment elevation in precordial leads (type 2). Two patients had documented ventricular fibrillation, ten patients had chest pain or tightness, and one patient had history of synocpe. Only one patient of all had family history of premature sudden death. Ventricular fibrillation was induced in 5 patients (38%) and wall motion abnormalities of right ventricle were detected in 3 (23%) patients. One patient showed the augmentation of the ST-segment elevation with coronary spasm. However, coronary angiography was normal in other 12 patients. Endomyocardial biopsy was abnormal in 7 patients (54%); fibrofatty infiltration with suggestive of ARVC in 2 patients and cardiomyopathy in 5 patients. Finally, 7 (54%) of 13 patients showed wall motion abnormalities or abnormal findings on endomyocardial biopsy, compatible with organic heart disease. Conclusions: Some patients with ST-segment elevation in right precordial leads were associated with evidence of underlying heart disease.