Early treatment for congenital dislocation of the hip is usually simple and inexpensive. However, if the disease is not detected by 6 months of age, treatment is often complicated and expensive. We evaluated the potential cost-saving of screening, by examining the costs in 36 late cases born in 1980 and found an average cost of pounds 6,674 per case for treatment to this date. This amount could justifiably be spent on each case detected in an effective screening programme.