After identifying six stages in the development of idiopathic aseptic necrosis of the femoral head in a refrospective study of fifty-three patients with bilateral disease, the results in the treatment of eleven asymptomatic hips (Stages 1 and 2) by Phemister-type fibular and tibial bone grafts were analyzed. Using a defined rating system based on the amount of change after operation in the stage of the disease and in the Iowa hip rating, seven hips were classified satisfactory; three, fair; and one, poor, in which the grafts were not placed properly. From these cases it was concluded that this procedure is warranted in the treatment of the silent (asymptomatic) hip in selected patients with bilateral idiopathic aseptic necrosis.