Single coronary artery is a rare congenital anomaly and is commonly associated with other congenital cardiac malformations. This report describes a 42-year-old man with an isolated single coronary artery, in whom the right coronary artery did not originate from the aorta but rather from the distal left circumflex artery. This patient did not have any other cardiovascular anomaly. However, he experienced angina pectoris and evidence of myocardial ischemia. Coronary angiography revealed insignificant coronary artery stenosis. He received medical treatment and responded well. An isolated single coronary artery is extremely rare, and this case may be only the 12th case reported in the literature.