The results of treating 148 hips in 135 children (aged 7 to 16 at the onset of management) for Perthes' disease are analysed. Cases are classified according to the amount of epiphysial containment and the results assessed according to the degree of preserved sphericity. It is concluded that to obtain satisfactory results in this age group treatment should be prolonged until the restitution of the epiphysis so as to maintain the initially achieved containment throughout the reparative process. Containment should be secured initially as follows: by non-operative treatment, in children aged seven to nine years with contained and also with slightly subluxated epiphyses; by femoral osteotomy, in children aged seven to nine years with severely subluxated epiphyses and also in children aged 10 and more with slightly subluxated epiphyses; by Salter's osteotomy, in children aged 10 years and more with contained epiphyses; by Chiari's osteotomy, in all crushed but smooth epiphyses, and also in children aged 10 and more with severely subluxated epiphyses; and by cheilectomy, in all crushed and saddle-shaped epiphyses, but only during the regenerative stage of the disease.