Eleven hips of 11 patients (8 boys, 3 girls; mean age, 7.5 years) with a diagnosis of Perthes disease underwent distraction using an Ilizarov external fixator. All patients had one or more Catterall signs of poor prognosis, with four hips classified as Herring class B and seven as class C. Patients were followed for a mean of 36 months. Average time for wearing the fixator was 99 days (range, 40-150 days). After fixator removal, containment was lost in two more patients and was sustained in only four patients. The most common complication was pin track infection, which occurred in eight patients. The low rate of success found does not justify the routine use of this technique.