In this prospective study, 35,550 neonates were examined shortly after birth by a team of orthopaedic surgeons. They diagnosed 775 unstable or dislocated hips in 656 babies; there were two teratological dislocations. Treatment was first with a Frejka pillow and, if this failed to give a normal hip, a Pavlik harness at three months. Early clinical examination did not identify 21 infants who were found to have subluxation or dislocation of the hip at the three-month review. The number of missed cases declined during the study, however, reflecting the increasing experience of the examiners. One case of avascular necrosis occurred in the group treated from birth and one in the late-diagnosed group. Open reduction was necessary only in the two teratological dislocations. Experienced examiners are needed for accurate clinical diagnosis; and treatment should be started before the baby is discharged from the maternity ward.