Radiographic examination of infants' hips is still indicated sometimes in addition to the sonographic examination. The legs have to be kept in a neutral position. The pelvis should not be turned to the side or tilted. Hilgenreiner's acetabular index is preferred in the diagnosis of hip dysplasia. Long-term follow-ups of critical values show spontaneous improvement in some cases, but also joints with increasing dysplasia. Critical values between one and two standard deviations of our material and somewhat above have to be followed. The axial orthograde view of the hip as a lateral view of the femoral head is recommended in Perthes' disease to determine the Catterall groups more exactly than in the Lauenstein position. Arthrography is still indicated in dislocated hips that cannot be reduced into the socket because of a narrow cartilaginous inlet. Here the risk of avascular necrosis is high and traction is indicated.