In 1974, bipolar endoprosthesis was first introduced by Bateman & Giliberty. It has theoretical advantages including minimizing acetabular wear, possible reduction of incidence of stem loosening, lessening of dislocation and easy revision procedure. Various methods for the treatment of fracture of the femur neck have been developed & performed, but it is still called “the unsolved fracture” in certain situation. But the role of it as primary treatment of fracture of the femur neck continues to be controversial. Current clinical results encourage its continued use and expansion of indication. Authors reviewed and analysed 21 cases of bicentric endoprosthesis and 1 case of Giliberty endoprosthesis those have been operated at the Department of Orthopaedic Surgery, National Medical Center from 1981 to 1983. Following results were obtained, l. According to disorder distribution, 14 cases were neglected fracture of femur neck, 2 old fracture, 1 idiopathic femoral head necrosis and 2 avascular necrosis & 1 non-union complicated by femoral neck fracture. 2. Among 20 cases, 8 cases were operated within 1/2 1 month after injury and 6 cases within 1 3months 3. Harris lateral appmach was used in 16 cases (80%) and Modified Gibson approach in 4 cases (20%). There were no significant differences in morbidity during operation and postoperative complication. 4. We used femoral stems those head diameter was 22 and 32mm(Charnley & Miiller type) and head pieces those diameter was 48-51 mm in male and 44–48 mm in Ifemale. 5. 3 cases were stiff in inner bearing without acetabular erosion. 6. In 6 cases more than 2 years followup 1 degree CE angle of Wiberg was increased in 2 cases of youngage respectively without associated hip joint pain. 7. Although inclination of head piece was vertical in 8 cases, fracture and dislocation were not found. 8. The circumference of head piece and opposite femoral head was measured and compared. There were 12 cases (mean 12.6 mm) that of head piece larger than opposite femoral head and 3 cases smaller than opposite femoral head. 9. There was 4 cases of complication (3 patients) and still no reoperation and revision converted to T.H.R. 10. With regard to average 18 months of follow-up, 7 cases of 81–90 Harris hip-rating score, 6 of 91–100, 4 of 71–80 and 3 of 61–70.