For a short-term evaluation of the patency of aortocoronary bypass vein grafts, 54 consecutive patients who underwent this operation alone were examined, irrespective of their functional state, 12.4 +/- 2.1 months after surgery. Examinations included coronary arteriography, selective opacification of the graft and ventriculography. The patients were 47 men and 7 women who had coronary arteriography for stable angina pectoris (22.4%) or a recent episode of unstable angina (59.3%) or a recent myocardial infarction (18.5%). Coronary arteriography showed one-vessel (5.5%), two-vessel (27.8%) or three-vessel (42.6) disease or stenosis of the main left coronary artery (24.1%). The mean number of distal anastomoses in multiple-vessel patients was 2.6. Peri-operative mortality was 1.04%, and the proportion of peri-operative electrocardiographic signs of necrosis was 11%. At the time of control examination, 82% of the patients had few or no symptoms, and 88% were improved by at least one functional class. 79% (97/123) of distal venous anastomoses were patent. All anastomoses were patent in 59% (22/54) and all were occluded in 7% (4/54) of the patients. Localized stenosis of the graft was found in 11% and diffuse stenosis in 4% of the cases. The patency of vein grafts was higher when the distal bed was of normal size than when it was small or poorly visualized at the initial angiography (85% vs 62%, p less than 0.01), or when the diameter of the artery bypassed was greater than 1.3 mm.(ABSTRACT TRUNCATED AT 250 WORDS)