An anomalous left main coronary artery with passage between the right ventricular infundibulum and aortic root has been incriminated as the causation of sudden death in a small number of individuals, many of whom are quite young. Mechanical features such as angulation and compression are most often incriminated. A 59-year-old man with such a coronary anomaly who had chest pain at rest, ST segment elevation, and ventricular tachycardia, but who had no evidence of effort-related myocardial ischemia, is reported. Improvement in the degree of coronary tone in the anomalous left main coronary with intracoronary nitroglycerin administration was demonstrated. This represents the first report of an individual with an anomalous left main coronary system with ventricular tachycardia/ventricular fibrillation and documented vasospasm in the anomalous artery.