Two cases of coronary artery aneurysm after percutaneous coronary intervention are presented. In both cases, follow-up coronary angiography revealed an expanding saccular aneurysmal formation and restenosis or a new lesion. Consequently, surgical repair and revascularization were indicated. The intraoperative angioscope was used to identify the aneurysm, which had not been visible on the heart surface in one case. Its optic fiber light was a useful guide, but little information was obtained from direct vision because of the small caliber of the angioscope. Plication of the aneurysm and bypass grafting distal to the aneurysm were performed. A whitish and thick-walled aneurysm was easily found in one case, in which ligation of the aneurysm was attempted with added distal bypass. The postoperative course was uneventful in both cases, and follow-up angiography showed disappearance of the aneurysm with patent grafts. There was a fragile thrombus inside both the aneurysmal sacs, which might have caused myocardial infarction and, therefore, justified the surgical repair of the aneurysm with concomitant revascularization. (Jpn Circ J 2001; 65: 52 - 55)