The special features governing roentgen examinations of the hip joint in children in respect of positioning, x-ray technique and radiation protection, are explained. Particular attention is paid to the criteria of an accurate focussing of the pelvis in infants. Furthermore, standard focussing procedures and x-ray symptoms are described for the following diseases and malpositionings: changes of the centre-collum-diaphysis angle (coxa vara, coxa valga), torsional hip, epiphysiolysis capitis femuris, aseptic necrosis of the femoral head (M. Perthes), and coxitis in babies, infants, and juveniles.