We report 3 young adult males who developed spontaneous ventricular fibrillation in the absence of demonstrable heart disease. Extensive clinical and electrophysiologic evaluation failed to disclose a cause for the arrhythmia. Antiarrhythmic drugs were empirically used in all patients but 2 of them eventually died. Thus, unexplained ventricular fibrillation without demonstrable heart disease carries a serious short-term prognosis. An implantable cardio-vector-defibrillator may be the therapy of choice in these cases.