Background. Disorders in development of the hip in the uterus are caused mainly by mechanical factors. Their influence has been established on the basis of the results of examinations of newborns from singleton pregancies. Malposition of the fetus and the lack of space in the uterus are present in higher frequency in twin pregnancies. Thus, it is probable, that twin pregnacy may be a risk factor in developmental dysplasia of the hip. <br /> Material and methods. We examined clinically and ultrasonographically 308 hip joints of 154 newborn twins and compare the values of the alpha related to different position in uterus, birthweight, gender, length of gestation and mode of delivery. The only pathological position of the fetus in the uterus is the tranverse one. <br /> Results and Conclusions. The results of ultrasound examinations reveal that in the cramped space inside the uterus in twin pregnancies hip joints develop in different conditions than in singleton pregnancies and the twin pregnancy cannot be regarded as a risk factor which may cause developmental dysplasia of the hip.