An operation was developed to prevent the formation of calcaneocavus deformity in growing children after poliomyelitis involving the calf muscles. Twenty operations have been done; ten of these patients have had an adequate follow-up (Table I). We believe that in selected cases of calf-muscle paralysis this procedure will prevent calcaneocavus deformity from developing in the growing child. We have also demonstrated that considerable power of plantar flexion of the foot can be developed. We have used combinations of any three of the muscles in the back of the thgh namely,the semitendinosus (for its length of tendon), the gracilis, and the semimembranosus, or the biceps femoris muscle for additional power. We believe the biceps is an ideal muscle to include in this tendon transplant because of its excellent power and the fact that it is a one-joint muscle in part due to the short head having its origin on the femur.