The patients of developmental dislocation of the hip(DDH) are almost found after walking age because of early diagnosis of DDH in younger children is not easy. A controversy still exists as to the relative value of closed and operative management in the treatment of a child who has reached walking age. This study is a report of the results of 16 patients(17 cases) in developmental dislocation of the hip who have visited our hospital at the age of 9 months to 3 years old, and have been followed more than 12 months (12-112 months) on review of plain radiographs and arthrograms. The results were as follows 1. The age at diagnosis was 16.4 months(9-31 months) in average. The methods of treatment were conservative for 8 cases, and operation for 4 cases and secondary operation for 5 cases who were failed with conservative therapy. 2. By Severin's radiologic grade, the result was good in 4 cases, fair in 3 cases and poor in 1 case in conservative treatment. In operative treatment, fair was in 2 cases and poor in 2 cases. In secondary operative -patients who were failed with conservative therapy, good was in 2 cases, fair in 2 cases and poor in 1 case. 3. Avascular necrosis of femoral head was developed in 3 cases. 4. In the good reduction as determined by arthrogram according to Race and Herring, we can get a favorable result in conservative treatment, and in the poor reduction as determined by arthrogram, the better