Two cases of complications of femoral artery cannulation in aortic arch related operations were reported. In the first case of them, we encountered massive cerebral infarction after concurrent CABG and aortic arch aneurysm operation. The patient also had untreated abdominal aortic aneurysm with mural thrombus. It was strongly suspected that retrograde perfusion from femoral artery cannulation made the mural thrombus free and the cerebral embolism subsequently occurred. The second case was acute aortic dissection with massive aortic valve regurgitation. Ascending and arch aorta replacement with resuspension of aortic valve was performed under selective cerebral perfusion. After the operation, myonephropathic metabolic syndrome appeared maybe for occlusion of femoral artery during cardiopulmonary bypass. The patient needed to receive hemodialysis therapy for three weeks after the operation. Through these two cases of complications of femoral artery cannulation, the potential of trouble in retrograde perfusion from femoral artery was noted. After these experiences, we planed to avoid retrograde perfusion from femoral artery as far as possible, especially in cases with mural thrombus or possibly detachable atheroma in ether descending or abdominal aorta. In cases, in which femoral artery cannulation can not be avoided, the duration of femoral artery occlusion should be made as short as possible. In order to shorten the duration, we usually make one supplemental branch in aortic prosthetic graft. After completion of aortic reconstruction, the perfusion in the rewarming period is made through the supplemental branch and the femoral artery can be perfused earlier. This supplemental branch is useful in preventing myonephropathic metabolic syndrome after surgery, especially in cases of prolonged cardiopulmonary bypass time.