This study concerns the results of treatment of 39 patients with 40 tibial fractures which had progressed to nonunion and which subsequently were treated by autogenous bone grafting and cast immobilization. Thirty-one fractures were initially open and nine of these became infected nonunions. Thirty-four fractures united after bone grafting, four other patients finally required amputations, and two tibiae healed after subsequent internal fixation. The functional results, especially as related to the ankle and subtalar joints, the residual tibial deformities, shortening and cosmetic results, were less than optimal. The difficulty with correcting and maintaining correction of the initial deformity and long periods of joint immobilization contributed to these results. Each patient with a nonunion of the tibia should be assessed so that a recommendation as to the need for immobilization, its type, and the necessity for bone grafting or not can be made.