We reviewed forty-four consecutive cases of simultaneous fracture of the ipsilateral femur and tibia in forty-two children and adolescents. One patient died from concomitant cerebral injury and one had a fat-embolism syndrome. Thirty patients (thirty-two limbs) had an average follow-up of 5.1 years (range, one to fourteen years). Nineteen patients who had an average follow-up of 6.8 years were available for personal examination and roentgenography. Age was found to be the most important variable as related to clinical course. Of the fifteen patients who were less than ten years old, three had an early complication; the average time to full, unsupported weight-bearing was thirteen weeks; and the average combined femoral and tibial overgrowth was 1.8 centimeters. Of the fifteen children who were more than ten years old, eight had an early complication; the average time to full, unsupported weight-bearing was twenty weeks; and there was variable femoral and tibial growth. The juxta-articular pattern of fracture was associated with the highest incidence of early and late problems. Most of the children who were younger than ten years were treated successfully with closed methods, but limb-length discrepancy developed. The children who were older than ten years were treated successfully with reduction and fixation of the femoral fracture, but had a high rate of complications. There was a high incidence of concomitant injuries to the ligaments of the knee, resulting in long-term dysfunction of the extremity. Of the nineteen patients who had long-term follow-up, only seven had normal function without major problems. The remainder had a compromised result due to limb-length discrepancy, angular deformity, or instability of the knee, particularly ligamentous instability.