Sixteen patients were studied prior to and after total hip replacement with an apparatus designed to eliminate all sensory cues to the perception of the position of the joint, except stimuli from the joint capsule and periarticular soft tissues. The detection of passive movement and its extent and the ability to duplicate positions of the hip at will were studied shortly after recovery from the operation and after several months. The ability to detect joint position, which was retained in the patients operated on, showed that the stimuli for position sense are not dependent on the joint capsule or the surfaces of the hip joint.