A 3-month-old infant developed signs of cardiac failure, which was initially attributed to cardiomyopathy. At 8 months, further investigations showed evidence of myocardial ischaemia with reversal of the flow of blood in the left coronary artery, which received no demonstrable inflow from the aorta. An anomalous connection of this artery with the pulmonary trunk was diagnosed but, at surgery, it was found that the arterial orifice was completely atretic, although the main stem was of normal size. A left internal thoracic arterial graft to the anterior descending coronary artery was performed, but he died on the third day after the operation. Postmortem examination showed a small dimple within the aorta at the site of the orificial atresia, extensive myocardial infarction, and two zones of myocardial bridging of the anterior descending coronary artery. We discuss the relationship of coronary orificial atresia with single coronary artery. Although they are related, they typically have different and contrasting clinical presentations. The possible role of the myocardial bridging is also considered.