We evaluated exercise tolerance and cardiorespiratory responses to exercise in patients with atrioventricular discordance (AVD) and abnormal ventriculoarterial connection after anatomic repair. Cardiopulmonary treadmill exercise testing with gas measurement was done 62 times in 19 patients with AVD who had undergone anatomic repair at the National Cardiovascular Center. Exercise duration, oxygen uptake (SymbolO2) and heart rate at anaerobic threshold and peak, and oxygen pulse during exercise were significantly lower in patients with AVD after anatomic repair than in controls. Carbon dioxide ventilatory equivalent during exercise was worse in patients with AVD after anatomic repair than in controls. Percentage peak SymbolO2 significantly correlated positively with percentage peak oxygen pulse and tended to correlate positively with the heart rate increments. Patients with AVD after anatomic repair exhibit impaired responses of heart rate and oxygen pulse with lower exercise capacity. Careful attention should be paid to patients with AVD after anatomic repair in terms of their functional capacity as well as other postoperative complications.