Ten measurements were taken to give a satisfactory description of the shape of the hip bone in thirty-two hip bones represen ting both sexes of rabbit, cat, fruit bad and man. Bipedes as man, has a specific long and wide ilium as a whole, long and wide caudal part of ilium and longest acetabulum. These characteristic measurements are attributed to withstand the effect of compression of the body weight and the demands of the erect posture. Quadrupedes as rabbit and cat, have a specific long ischium and long and wide ischial tuberosity to withstand the effect of propulsive forces of the body forward during quadrupedal locomotion and in digging and leaping habits respectively. Also, quadrupedes have specific long pelvic symphysis ischio-pubic symphysis, which is the main factor in supporting the pelvic viscera. Fruit bat has a specific long pubis, but it seemest to have no role in deve lopment of posture. A great deal of behavioral variations in rabbit, cat fruit bat and man are possible with little differences in the measurements of the hip bone.