2237 infants (1210 females, 1027 males) aged two days-six months were screened by ultrasound for congenital dysplasia of the hip (CDH). 21 infants (0.93%) were detected having CDH by ultrasound examination. We have evaluated the concordance between ultrasonography, clinical examination (Ortolani's examination) and risk factors. Of the 21 infants with CDH, 10 (47.6%) had a positivity of Ortolani's examination, 13 (61.9%) had at least one risk factor, 3 (14.2%) had a negative clinical evaluation and no risk factors. Our data indicates the superiority of ultrasonography as compared with physical examination alone, for the diagnosis of CDH. Infants presenting any risk factors for CDH and/or a positive Ortolani's examination should have an early ultrasound evaluation in order to allow initiation of treatment early on, while in infants with negative clinical findings and no risk factors, it should be postponed to avoid the frequent finding of physiological immaturity of the hip. The finding of a high rate of infants that presented a grade IIA in the Graf's grading system during their first month of life and that evolved favourably in the absence of risk factors, and which required further sonograms, indicates the period between the second and the third month as the most desirable for ultrasound screening of CDH.