AIMS--To examine veins histologically from different sites in the body to study the effect of venous pressure; and to examine veins used as aortocoronary grafts. METHODS--The axillary vein, femoral vein at the inguinal ligament, the short saphenous vein at the knee and the long saphenous vein at the ankle were removed from 24 necropsy cases of patients aged 2 months to 80 years. Fifteen varicose saphenous veins and 12 aortocoronary grafts removed at surgery were obtained. All were examined histologically. RESULTS--Varying degrees of intimal thickening composed of collagen, elastin, and smooth muscle were found. These changes were most noticeable in the varicose veins. Intimal changes were also seen related to valves and to adjacent arteries. No clinically relevant lipid was seen in the native veins, though atheromatous changes were seen in the grafts. CONCLUSIONS--Venous changes are related to venous pressure, to local haemodynamic effects, and probably to hypoxia. The changes are often focal and seem to be sequential in their formation. True atheroma is seen in the aortocoronary grafts but is not seen in native veins and this may be the result of additional factors.