Left circumflex coronary artery anomalies are rare causes of cardiac symptoms, especially in the adult population. Herein we describe a case of a 40-year-old man presenting with stable angina who was found to have aneurysmal formation and fistulization of the left circumflex coronary artery to the coronary sinus. Contrast-enhanced multislice computed tomography was very useful in our case for the diagnosis of such anomalies.