To determine the blood flow in healthy femoral arteries electromagnetic measurements were made on common femoral, superficial femoral and profunda femoris artery in 20 patients during operation for varicose veins. The values obtained were 239 ml/min, 134 ml/min, and 104 ml/min respectively. These registrations were compared with those achieved during reconstructive arterial surgery. It was found that the average basal flow values from corresponding arteries were rather similar. The flow values registered from femoropopliteal bypass grafts were identical with the flow values from the superficial femoral artery of varicose patients. The papaverine response of the common femoral artery flow was tested in 7 varicose patients. The average increase was 250%. None of the average responses from various arteries during arterial reconstructive surgery reached this value. The papaverine responses in femoropopliteal bypass grafts were closely correlated with the arteriographically estimated outflow potential. The flow values both at rest and during vasodilatation showed a great range in all vessels measured.