There have been much controversy about prosthetic replacement or internal fixation for patients over 70 years old. Authors reviewed and analyzed 45 cases of cemented bipolar hemiarthroplasty in patient over 70 years treated at the Department of Orthopedic Surgery, Sung-Ae General hospital from January l988 to July 1995. The purpose of this study was to analyse the clinical and radiological results and to detect the motion study of bipolar cup. Follow up period was average 26.1 months, ranged from 24 months to 37 months. The following results were obtained. l. In clinical evaluation, excellent & goad result were in 31 cases(68.87o). 2. In radiologic evaluation, acetabular erosion were in 2 cases and loosening of the femoral component was in 1 case. 3. With time elapsed, the amount of the inner bearing motion was decreasing with preservation of the total joint motion. 4. Complications were idiopathic pain 7 cases, nerve paresis 2 cases, superficial infection 2 cases, intraoperative fracture I case, dislocation I case, loosening 1 case.