A prospective neonatal screening programme for congenital dislocation of the hip is reported. This covered over 20,000 live births including all the babies born in one area, with a virtually complete follow-up. All babies were examined within the first seven days of life and all hips which were dislocated or unstable after four days (1.6%) were splinted. Only two screened cases were "missed" and subsequently detected at 15 and 18 months. No later cases were discovered, and patients between 10 and 20 years of age had apparently remained asymptomatic. The detailed results show that neonatal screening is effective in detecting and preventing a crippling disorder in otherwise normal people. The examination, though brief, is difficult to perform well; it is considered that failure of the method lies with the examiner and not with the tests.