The authors report their experience with US of the hip in 1000 children aged 1 day to 8 months. US study was carried out following Graf's method. All the children were previously examined by a pediatrician, who recorded all the clinical signs on a chart. After US examination, the radiologist recorded US findings on the same chart. Thus, US findings could be compared to clinical ones: there was agreement in 71% of cases, and disagreement in the extant 29%. Furthermore, clinics exhibited a high false-negative rate (64%) and a low false-positive rate (23%). This suggests US as an useful screening method able to show early morphological and functional alterations in the infant hip. The authors also examined the incidence of the single clinical signs and risk factors, and correlated them with US findings.