The intra-articular pressure of the hip joint of a hemipelvectomized limb was measured outside and inside the limbus. The negative pressure inside the limbus was not sufficient to hold the weight of a leg. The pressure inside the limbus changed chiefly in flexion, extension and internal rotation, however, the pressure outside the limbus changed primarily in abduction, adduction and external rotation. From these pressure changes, it was considered that the limbus was not an airtight valve. Moreover, there seemed to be an air leakage through valve of the limbus.