Biologic reconstruction of the femoral head by a sophisticated autotransplantation of the proximal growing fibula associated with a massive bone allograft has been performed in a 4-year-old girl affected by Ewing's sarcoma. The child was treated in 1997 and then followed: clinical and functional tests were performed 2, 3, 4, 6, and 7 years after surgery. Gait and specific motor tasks were assessed by means of motion analysis instruments. The patient was followed by a specific rehabilitation program, aimed at controlling load on the treated limb, resuming good muscle function, and recovering a physiological pattern of movement during daily routine activities. The outstanding radiographic evolution 8 years after surgery with the peroneal head progressively remodeled as a femoral head, and the more than satisfactory gait pattern observed at last follow-up, makes this study a keystone of experience and knowledge to be applied to other patients.