An uncommon coronary anomaly incidentally found at autopsy of a 76-year-old woman is reported. There was no history of cardiovascular symptoms or clinical signs of ischemic heart disease. The autopsy disclosed that the patient had no left coronary ostium and that the left main coronary artery was atretic. However, the rest of the left coronary system, including the left anterior descending coronary artery and the left circumflex coronary artery, were intact in their normal positions. Arterial flow to the left coronary system was supplied by a dilated collateral vessel that originated from the right main coronary artery and coursed between the right ventricular infundibulum and the aorta. Our case suggests that atresia of the left coronary ostium and the left main coronary artery, often associated with death at an early age, may also be compatible with symptom-free longevity. Moreover, attention is focused on the nomenclature of single coronary anomalies.