A 60-year-old man with hypercholesterolemia and hypertension presented with acute coronary syndrome (SCA). The ECG showed lateral ischemia (T-wave inversion in V4-V6, D1 and aVL) and echocardiography showed normal left ventricular wall motion. Coronary angiography showed critical atherosclerotic lesions in the distal part of the left circumflex artery (LCx, culprit lesion), chronic total occlusion of the right coronary artery (RCA), significant but not critical stenosis in the middle part of left anterior descending artery (LAD), and a coronary artery to pulmonary artery (PA) fistula originating from the proximal part of the LAD and emptying into the PA via a coronary saccular aneurysm (12 x 12 x 10 mm). A multidetector row computed tomography angiography (CTA) confirmed the coronary artery fistula, which was treated with surgical approach. The patient underwent aneurysmorrhaphy with CAF closure and coronary artery bypass grafting on the RCA and LCx. The postoperative course was uneventful and the patient was discharged on postoperative day 14. CTA was useful for understanding the spatial relation of the CAF and the connection with the PA.