Hypercholesterolemia is a recognized risk factor for development of atherosclerosis in both native coronary arteries and bypass grafts. Lipid-lowering therapy with statins is effective. Few data are available for studies on bypass grafts. The influence of hypercholesterolemia on development of bypass graft disease was studied. Clinical and angiographic follow up 1yr after CABG of patients with a preoperative cholesterol >6.2mmol/l, with a preoperative lipid control (group 2) or controls (group 1) and patients with cholesterol <4.7mmol/l (group 3) were studied. Patient demographics, angiography and operation data were the same in all the groups. Group 1 patients had significantly higher incidence of graft lesions, requiring more interventions than Group 2. Sequential vein bypass grafts showed superior features compared to single vein grafts. Preoperative lipid control with statins is strongly recommended, since uncontrolled hypercholesterolemia has a direct impact on the outcome of CABG procedure. It significantly reduces the development of vein graft obstructive disease.