This article reviews briefly the history of the use of vein grafts for arterial repair. It concentrates upon the various reports of success and failure rates with this procedure, particularly in coronary artery and femoropopliteal bypass operations, and compares the two. Special emphasis is given to the two major intrinsic reasons for graft failure: intimal hyperplasia and atherosclerosis. Both of these are discussed with reference to the experimental evidence available to show the various factors that might be involved in the pathogenesis of these conditions.