Aneurysm formation in saphenous vein aortocoronary bypass grafts is an extremely rare complication of coronary artery bypass surgery. Aneurysms of native coronary arteries are found in a small percentage of patients at autopsy. Reported is a case with multiple coronary artery aneurysms in which a dissecting aneurysm of the saphenous vein bypass graft also developed following coronary artery bypass surgery. This is the first report of such association. Copyright © 1982 John Wiley & Sons, Ltd.