The bipolar endoprosthesis was first reported by Giliberty, as well as Bateman in 1974. There were several reports indicating less acetabular erosion in bipolar endoprosthesis than in unipolar, Even if there was a problem of dislocation and valgus position of cup of initial design, the prosthesis of nowadays is useful in failed total hips with erosion of the acetabulum as well as hip with normal acetabular cartilage. The authors reviewed and analysed 44 cases of cementless bipolar endoprosthesis (Self Centering Universal Hip replacement utilizing the Tri-Lock total hip femoral stem), operated at the department of orthopaedic surgery, Hanyang University Hospital from June 1984 to May 1987. The following results were obtained. 1. There were 18 males and 25 females. 2. 22 cases were idiopathic avascular necrosis with relatively good acetabulum, 21 cases of fracture of femoral neck and 1 case of metastatic adenocarcinoma. 3. Average operation time eas 1 hour and 10 minutes and average amount of transfusion; 650cc. 4. We used 42 Watson-Jones approach and 2 Charnley's. 5. The common size of metal cup was 45–53mm in men and 43–47mm in women. 6. The size of prosthetic femoral head was equal to normal head in 16 cases, larger than normal in 14 cases, smaller than normal in 14 cases. 7. There were 2 case of intraoperative undisplaced fracture of femur and one case of heterotopic ossification. 8. There were motion of outer and inner bearing when the extremity was abducted and adducted on serial roentgenogram during a period between 2 years and 5 years. 9. Average Harris hip rating score was 38.5, preoperatively and 95.2, postoperatively.