Although arterial conduits are widely used and have improved the long-term results of coronary artery bypass grafting,vein grafts remain important additional conduits in coronary surgery.Newer studies show a saphenous vein graft patency of 60% or more at 10 years postoperatively.Vein graft occlusion occurs as a result of neointimal hyperplasia,which takes place in response to hemodynamic changes,vessel wall injury and thrombosis,and is characterized by the migration and proliferation of vascular smooth muscle cells.Intimal hyperplasia is further complicated by the concomitant development of atherosclerosis.In this review we will summarize the pathogenesis of coronary vein graft disease.