The definition of underlying heart disease in apparently idiopathic ventricular fibrillation seems to be important in regard to prognosis and choice of therapy. From October 1989, until August 1993, cardiac arrest due to the documented ventricular fibrillation occurred in eight consecutive patients with normal results on clinical examination, normal echocardiography, and normal or apparently nonspecific electrocardiogram (ECG) findings. Complete invasive investigations, including selective right ventricular angiography, were done; regional hypokinesia and segmental bulging of the right ventricle were found in seven patients (88%). Arrhythmogenic right ventricular dysplasia was suspected in these patients, although endomyocardial biopsy was not performed. After the finding of localized right precordial QRS prolongation of more than 110 ms in November 1993 in five patients, a retrospective, a more precise approach to QRS duration in standard ECG supported this diagnosis. Selective right ventricular angiography is of great help in identifying underlying heart disease in patients with apparently idiopathic ventricular fibrillation, and confirms ECG findings.