Forty-nine skeletally mature patients who had either a non-union or a malunion of a fracture of the tibia or the femur had correction of the deformity and acute axial lengthening of the fractured bone. Distraction was provided by the short AO/ASIF fracture distractor applied directly to the site of the osteotomy or non-union. At an average of sixty-three months (range, twenty-six to 105 months), the average increase in the tibial and femoral length was 1.7 and 3.2 centimeters, respectively. There were no compartment syndromes or ischemia secondary to any of the procedures. One patient had a transient sensory-nerve loss. Fatigue fractures were seen in two tibial plates, two femoral plates, and one femoral intramedullary nail used for osteosynthesis. A non-union developed after four other femoral intramedullary nailing procedures. One infection developed after lengthening of a tibia. Restoration of normal length by acute lengthening and internal fixation was achieved in twenty-seven patients. One patient had overlengthening of one centimeter. Fifteen patients had residual shortening of approximately one centimeter, three had shortening of more than one to 2.5 centimeters, and three patients had more than 2.5 centimeters of shortening. The patients in this series had acute restoration of limb length after traumatic shortening with a low prevalence of complications of neurovascular compromise. Three of the thirty tibial lengthenings and seven of the nineteen femoral lengthenings had to be followed by at least one additional procedure to obtain union.