In the past, congenital dysplasia and dislocation of the hip joint have, despite treatment, led frequently to late sequals (deformations and incongruous articular surfaces), requiring repeated corrective interventions. Nevertheless, life-long handicaps could not always be prevented. It is known for a long time that sequels, such as articular deformations and desorders of growth of the femoral head, can be prevented the better, the earlier the treatment is initiated. However, a reliable method for early diagnosis has been lacking to date. Even systematic clinical examinations of all newborn babies have not been able to prevent late appearance of dysplasia and dislocation. This is not due to poor practice of clinical examination, but is explained by to day's knowledge that most dislocations are not present at birth but develop later on. Deformations of the acetabular roof without any dislocation of the femoral head are clinically not papable and do not cause any symptoms in adults until the onset of coxarthritis. Hip sonography according to Graf has proven to be an effective imaging procedure for early diagnosis. Right at birth, it allows very reliable detection of all cases that, if left untreated, will cause later major therapeutic difficulties, such as dislocations of the femoral head or coxarthritis due to dysplasia of the acetabular roof. If diagnosed early--at best immediately after birth--successful healing can be achieved even in severe cases resulting in an anatomical and functional normal hip joint, only by conservative and out-patient treatment. That is why many centers have established sonographic screening programs of all newborns as a preventive measure. Screening is medically most effective, if practiced at the earliest possible stage (at best immediately after birth). From an economical point of view, no disadvantage of early screening (despite of higher rates of findings requiring review) has been found in terms of overall costs (screening, follow-up, treatment).