Hip arthrogram is often requested for both congenital hip dislocation and Legg-Calve-Perthes disease in pediatric age group and has been known as a valuable procedure to evaluate the contour of cartilaginous femoral head, and the relationship of acetabulum and femoral head, which are not observed on plain film, But, arthrogram is an invasive study, and we have experienced a number of confusions for its role in taking care of patients involved in congenital dislocation of the hip and Legg-Calve-Perthes disease. For this reason, centered on its significance in determining treatment plan and predicting prognosis, we retrospectively reviewed 41 arthrograms in 36 patients; 16 arthrograms of congenital dislocation of the hip in 13 patients and 25 arthrograms in Lee-Calve-Perthes disease in 23 patients, which were performed at Department of Diagnostic Radiology, College of Medicine, chungnam national University from January 1985 to May 1989. The results were as follows. 1. Congenita dislocation of the hip 1) Under the fluoroscopic control we evaluated the possibility of closed reduction after injection fo contrast media into the joint capsule and if closed reduction was not successful, obstacles to closed reduction were observe. As a result, failure of closed reduction was appreciated in 12 cases of 16 patients and inhibiting factors of closed verse acetabular ligament thickening : 10 cases, ligament teres thickening : 8 cases, iliopsoas muscle thickenign : 8 cases, capsular adhesion : 7 cases, other space occupying lesions such as fatty and / or fibrous tissue : 9 cases. 2) Hip arthrogram was an excellent method to evaluate the possibility of success of closed reduction and to find inhibiting factors of closed reduction before open reduction. 2. In Legg-Calve-Perthes disease Hip arthrogram was an useful means to evaluate deformity or irregularity of cartilaginous femoral head, enlargement and lateral extrusion of femoral head, and incongruity of hip joint, but it was not satisfactory to determine treatment plan and to product prognosis based on its findings during process of disease.