Coronary artery aneurysm is a rare form of ectasia characterized by a 50% or greater increase in coronary arterial diameter as compared to adjacent normal arterial segments [1]. One study observed aneurysms in as many as 4.9% of patients undergoing coronary angiography, most frequently with involvement of the right coronary artery, followed by the left anterior descending and circumflex coronary arteries [1]. Some investigators have noted an association with coronary artery stenosis and speculate that aneurysms may be pathologic manifestations of coronary atherosclerosis [1]. We report the rare case of a relatively healthy 43-year-old woman with aneurysm ofthe left main coronary artery and present the computed tomographic (CT) findings using 64-slice CT.