79 infants with congenitally dislocatable hips diagnosed clinically soon after birth were examined sonographically and randomised in a controlled trial to immediate splinting (n = 41) or sonographic surveillance for 2 weeks (38). Infants from this second group were splinted at age 2 weeks if instability persisted (11 of 38) or if sonographic abnormality had shown no improvement (4 of 38). Sonographic findings or clinical outcome did not differ between the two groups at birth or at 6 and 12 months' follow-up. We conclude that dislocatable hips may be safely watched for 2 weeks after birth to allow spontaneous resolution, but that this approach requires considerable resources and attention to detail. Our experience confirms the importance of the dynamic sonographic scan. The low specificity (70%) of sonographic examination in the first week of life makes it an unsatisfactory primary method of screening at birth, but it is a most useful adjunct to the clinical screening and management of congenital dislocation of the hip.