A single coronary artery is a rare congenital anomaly of the coronary arteries where only one coronary artery arises from the aortic trunk by a single coronary ostium, supplying the entire heart. We report a case of a 57-year-old woman with atypical chest pain, in whom coronary angiography showed a L-I subtype single coronary artery (arising from a single ostium in the left sinus of valsalva) without associated cardiovascular disease. The clinical significance and subtype of the single coronary artery are discussed.