Skin flaps from rabbit thighs were raised. The saphenous veins of the flaps were anastomosed with the femoral arteries.The valves in the veins were studied histologically. Fibrous tissue of the venous valve at the site of its junction with the venous wall underwent "fatigue" injury resulting in fracture of the valve.Theraby the valve opened according to the direction of blood flow, and the valvular tissue began to adhere to the venous wall.The results suggested that rapid blood flow with high pressure might remodel the venous valve in an arterialized venous skin flap.