In the experiments conducted with adult rabbits for tbe purpose to elucidate biological factors of intertrochanteric osteotomy in osteoarthritis of the hip, the following results were obtained. 1) After intertrochanteric osteotemy performed on adult rabbits in about 4 to 5 postoperative weeks there can be observed the dilataticn of blood vessels in the epiphyseal and the metaphyseal regions and hyperemia due to it reaches its maximum, but by about 8 to 10 weeks it returns practically to normal. 2) Intertrochanteric osteotomy in man is most beneficial for serve pain and its ill effect is the limitation of movement. However, in the bilateral case its applicability should be decided with utmost care and it becomes necessary to obtain the hip joint having monolateral support. 3) In discussing about intertrochanteric osteotomy its effect is mainly taken up from its mechanical aspect, but its biological significance should also be given a due attention. Therefore, in discussing what operative procedure needs to be selected, this latter point must be borne in mind.