Girdlestone operation is a resection arthroplasty, which is composed of resection of head and neck of femur and construction of pseudoarthrosis, which was described by Girdlestone at first in 1928. The purpose of this study was to establish the efficacy of Girdlestone operation. In 4I hips of 40 patients, who had undergone Girdlestone operation and was not converted to total hip replacement from Dec. 1986 to Sep. 1996, were reviewed. Average follow up period was 3 years and 10 months(range from one year to ten years and ten months). Twenty four patients (25cases) were males and sixteen patients were females. The average age was 49 years old(range from 19 to 77 years old). Preoperative diagnoses were infection in 32 cases, posttraumatic osteoarthritis in 3 cases, pelvic bone fracture in 2 cases, ankylosing spondylitis involving hip joint in 2 cases(1 patient), RDC(rapidly destructive coxarthrosis) in one case and femoral neck fracture in one case. Pain was relieved completely or decreased markedly in all cases after Girdlestone operation. Preoperatively, four patient(five cases) had not been able to walk and thirty six patients had showed the moderate or severe limping. After operation, thirty cases showed the moderate 1imping. In the analysis of walking grade, preoperatively, four patients(five cases) had not been able to walk and 36 cases had used cane or crutch, postoperatively, 16 cases walked without any support, 9 cases used one cane, and 16 cases used two crutch. The range of motion of the hip joints was improved postoperatively. Preoperative flexion contracture, average fourteen degrees decreased to average three degrees postoperatively. Preoperative further flexion, average sixty eight degrees, increased to ninety degrees postoperatively. The average shortening of operated limb was 4.5 cm. Average time interval from operation to crutch ambulation was 37 days. In the assessment of patient satisfaction, most patients were satisfied with the improvement of pain, physical activity and psychosocial activity except morphological change. Our opinion is that Girdlestone operation is relatively an effective and safe procedure to treat the infected or dysfunctioned hips.