The influence of smoking, hyperlipidemia, and glucose intolerance on graft patency and rate of progression of obstructive disease in the native circulation was assessed in 99 patients 1 1/2 years after aortocoronary bypass grafting. There were 24 patients in whom none of these risk factors was identified. There were 42 patients with one, 29 with two, and four with three risk factors. Overall graft patency rate was 74%. Graft patency was not significantly influenced by any of these factors either singly or in combination. Progression of obstructive disease in both proximal and distal segments of grafted vessels and in nongrafted vessels was not significantly increased by the presence of one, two, or three risk factors. Over all, there was progression in 56% of segments proximal to grafts, in 8% distal to grafts, and in 14% of nongrafted vessels. Longer term studies will be required to establish any adverse influence of these risk factors on saphenous vein bypass grafts and native circulation.