One hundred twenty-one patients with avascular necrosis of the femoral head in adults, who were admitted in Department of Orthopadic Surgery, Kyungpook National University Hospital between January of 1972 and June of 1986 are investigated in terms of the history, clinical data, radiographic findings and laboratory examinations. And, the following results were obtained. 1. The highest incidence was in the 5th decade and the sex ratio between male and female was 5: l. 2. 62 cases(51.2%) had the bilateral hip involvement, and higher incidence of bilateral hip involvement in steroid or alcohol induced cases. 3. Etiological factors were unknown(38 cases, 31.4%), steroid (31 cases, 25.6%), alcohol (22 cases, 18.2%), femur neck fracture (15 cases, 12.4%), trauma (13 cases, 10.7%) and caissons disease (2 cases). 4. Underlying diseases in steroid-induced avascular necrosis of the femoral head were dermopathy (8 cases), pain over other joints (7 cases), head trauma (5 cases), nephropathy (4 cases), etc. 5. The time intervals between etiological events and appearance of clinical symptoms were 1 year and 7 months in steroid-induced cases, 1 year and 9 months in femur neck fracture cases, 1 year and 1 month in trauma-induced cases, 1 year and 5 months in caissons disease. 6. The duration of morbidity was 21 months on average. 7. At first hospital visit, the Ficat stage of femoral head avascular necrosis were stage II in 12 cases (10%), transition stage in 17 cases (14%), stage III in 34 cases (29%) and stage IV in 56 cases (47%). 8. Bone scanning was performed in 59 hips of 42 cases. Cold spot was observed in 17 hips and hot spot in 36 hips. There were false negative findings in 4 hips in spite of ischemic findings of femoral head on simple x-ray. 9. Bone marrow pressure was higher than 30mmHg and was increased 10mmHg more than initial pressure by stress test. 10. On intramedullary venography, diaphyseal reflux of contrast medium and diaphyseal stasis more than 15 minutes in 7 of 9 cases over stage II.