The surgical treatment of Perthes' disease by femoral or innominate osteotomy is not as effective in those over the age of eight years as it is in the younger child. This has prompted the search for other types of management in those who are older. The preliminary results of the use of a lateral shelf acetabuloplasty for such cases have shown encouraging results at two years. The concern with such an operation is that it might interfere with the growth of the outer aspect of the acetabulum and so prejudice the long-term outcome. We describe a review at maturity of 26 children presenting with early disease after the age of eight years who were treated by lateral shelf acetabuloplasty. The results suggest that the outcome is improved; 22 of 27 hips were rated as Stulberg groups 1 to 3. Poor results occurred in children, particularly girls, presenting with Group-4 disease over the age of 11 years.