We describe a case of a 60-year-old man with effort-induced angina pectoris. Coronary angiography showed an aneurysm in the proximal left anterior descending coronary artery. It was unclear whether it was a coronary artery aneurysm or a coronary fistula with an associated aneurysm. Three-dimensional reconstruction images from 16-slice multidetector row computed tomographic (MDCT) angiography showed an aneurysm that drained into the pulmonary artery. Images from 16-slice MDCT coronary angiography can be helpful in understanding complex coronary artery anatomy.