Real-time ultrasonography has been used for diagnosis and screening of developmental dysplasia of the hip for several years. If diagnostic criteria are well established, the use of sonography in follow-up of treated infants remains extremely variable. The aims of this study were (a). to describe the normal sonographic anatomy of the infant abducted hip on an anterior axial view, and (b). to define the role of this approach in the follow-up of developmental dysplasia treated by Pavlik harness. Thirty-eight patients with Pavlik harness had anterior axial sonograms in addition to their usual clinical and sonographic follow-up. Normal anatomy was inferred from the examination of 25 clinically proven normal hips in the same population. The best criterion of a normal positioning of the femoral head appears to be the alignment of the pubic bone and the femoral metaphysis. Pavlik harness was the only treatment in 32 patients. It was directly efficient in 22, after readjustment in 10 patients. Reduction was shown by anterior sonography in all of them. In 6 children, sonography showed no reduction and subsequent treatment by closed or open reduction was carried out. Anterior axial sonogram can show reduction of a dislocated hip in children with Pavlik harness, but it does not evaluate its stability. It helps optimize the settings of the harness, and may predict a poor outcome, but it does not identify the cause of non-reducibility.