Twenty-one patients with tetralogy of Fallot following intracardiac repair underwent a treadmill test for evaluation of their exercise capacity. They were divided into two groups according to their post-operative hemodynamic status, the good result group and the poor result group. The maximum oxygen consumption during exercise was significantly decreased in the poor result group, but that of the good result group showed no significant difference from the control group. However, the maximum heart rate in both the good and the poor result groups was significantly lower than that of the control group. Thus, the exercise tolerance in post-operative tetralogy patients was found to be within the normal range as long as their hemodynamic operative result was satisfactory, but the limited capability of increasing heart rate with exercise could present a potential problem in the long-term prognosis.