In patients with unilateral proximal femoral focal deficiency, the leg length inequality is almost always greater than five inches at skeletal maturity. Consequently, prosthetic management should be planned before the patient walks. A standard plan of treatment of the patient with unilateral PFFD is not possible at this time, primarily because of the varying percentage of femur missing and the controversy of management of the hip in patients with type A or B deformity. However, we found that ankle disarticulation with Syme flap closure combined with arthrodesis of the knee is a reasonable plan in many patients with unilateral PFFD. This allows correction of the knee and hip flexion contractures and gives the patient a functional, cosmetic stump. By the time he begins school, he is functioning as an above-knee amputee. This is not an undesirable goal, as one of us (E.G.R.) recently examined an above-knee amputee, a Captain in the United States Army, who continued his hobby of sky diving.