To evaluate the relationship of functional results after aortocoronary saphenous bypass surgery, 66 patients of age 33--65 yr (mean 52) underwent a standarized bicycle exercise test before and an average of 14 mth after operation. Capacity of exercise was correlated with symptomatic response and graft patency. Group exercise tolerance was significantly improved after operation, and was about 60% of that of a population-based series of 52-yr-old men [6]. After operation 74% of the patients could exercise to fatigue without apparent limiting cardiac symptoms, while 26% still were incapacitated because of angina. Improvement in tolerance for exercise correlated with symptomatic improvement as well as patency of the grafts; patients with no grafts remaining patent showed no improvement in exercise performance.