We studied 143 patients(218 hips) who were diagnosed osteonecrosis of the femoral head in Yonsei University Hospital between January, 1985 and December, 1989, and analysed the epidemiologic distribution and methods of treatment. The following results were obtained. 1. The peak incidence of age distribution was 5th decades. 2. The sex ratio between male and female was 4:1. 3. The most frequent etiologic factor was idiopathic(96 patients, 67%) and followed by alcoholic (23 patients, 16%) trauma(17 patients, 12%) and steroid induced(7 patients, 5%). 4. The bilateral hip involvement was 75 case(52%) and in steroid and alcohol induced cases, the bilaterality was higher(67%) than other causes. 5. At first hospital visit, the Ficat stage III were 43 hips(20% ), stage III were 113 hips(52% ) and stage IV were 62 hips(28%). 6. We performed core decompression and/or bone graft without siginficant effect, but vascularized fibular graft with significant effect in stage II, and hemiarthroplasty or total hip replacement in stge III, IV.