One of the main purposes in the treatment of developmental dislocation of the hip is to achieve and maintain concentric, congruent, and stable reduction. The arthrogram performs an important role in the diagnosis and treatment of developmental dislocation of the hip. The arthrogram provides much information about the soft tissue status of the hip joint. Limbus and ligamentum teres is exactly evaluated so that we can plan the reduction and treatment before operation. Eighteen preoperative hip arthrograms of 17 children treated for developmental dislocation of the hip from 1992 to 1998 were reviewed. The limbus, ligamentum teres and transverse acetabular ligament were compared with the pathoanatomy seen at the time of open reduction. Arthrography proved to be reliable in identifying the limbus and ligamentum teres. So we recommend that arthrography must be performed before closed or open reduction. Also, we recorded the radiographic parameters: acetabular index, acetabular floor thickness, center edge(CE) angle of Wiberg, and Y-coordinate. The center edge(CE) angle of Wiberg obtained from arthrography was measured more accurately than from simple roentgenograms because the ossification of the femoral head was frequently located eccentrically in the developmental dislocation of the hip.