Three hundred seven newborns were examined clinically and by ultrasound for congenital dysplasia of the hip (CDH). The purpose of the study was to determine the prevalence of sonographic abnormalities and to discover if sonography could be helpful in detecting cases of CDH that would be missed by clinical diagnosis alone. Eighty-two hips (13.4%) had ultrasound abnormalities despite a normal clinical examination. Of these, three developed definite hip dysplasia. The remaining 79 hips became clinically and sonographically normal within 12 weeks. Ultrasound visualized and recorded the dislocation-reposition maneuver of three other hips that were clinically dislocatable at birth. Dislocation occurred in a craniodorsal direction.