We estimated the frequency of anatomic variations in origin of the left coronary artery in a Turkish population by analyzing the angiographic data of 10,042 consecutive adult patients undergoing coronary angiography. Among 10,042 adult patients, 5 (0.04%) patients (4 men and 1 woman, age range 40-74, median 58 years old) had anomalous origin of the left main coronary artery. The left main coronary artery arose from the right coronary sinus of Valsalva in 2 (0.019%) patients (both of them had a retro-aortic course), from above the left coronary sinus of Valsalva in 2 (0.019%) patients, and from above the non-coronary (posterior)-left coronary commisure in 1 (0.009%) patient. Anomalous origin of the left main coronary artery is potentially a serious condition, as it can lead to myocardial infarction and sudden cardiac death under physical exertion. Therefore, greater effort for early detection and surgical repair of this anomaly are warranted. The angiographic recognition of anomalous origin of this vessel may prove useful for physicians dealing with diagnosis and treatment of anomalies of the left main coronary artery.