Atherosclerosis is the most frequent cause of occlusion of aortocoronary saphenousvein grafts between 5 and 10 years after coronary artery bypass surgery. The typical atherosclerotic plaque appears between 1 and 3 years after operation and, at a mean of 5 years, histologic changes of atherosclerosis are present in 21 % of grafts and in 27% of patients. Only approximately 60% of saphenous vein grafts remain patent at repeat angiography between 10 and 12 years after bypass surgery; 45% of patent grafts show atherosclerotic changes at angiography and 43% of patients show evidence of atherosclerosis in one or more saphenous vein grafts. We do not know whether the development or the progression of these atherosclerotic changes can be modified; however, the data currently available suggest that the administration of platelet inhibitors and/or of lipid lowering agents offer two promising avenues of investigation in patients undergoing aortocoronary saphenous vein bypass surgery. Until this has been carefully studied, the internal mammary artery should remain the preferred conduit for aortocoronary bypass grafting, whenever possible.