Thirty-two elderly patients with a femoral neck fracture treated by bipolar hemiarthroplasty and 36 patients (matched for age) with an Austin-Moore hemiarthroplasty were followed-up and compared. Bipolar replacement resulted in a higher percentage of satisfactory results, less postoperative pain, greater range of movement, more rapid return to unassisted activity, fewer unsatisfactory results and no acetabular erosion. The device functioned as bipolar in all the cases studied for inner-bearing motion.