A total of 102 children, aged 1-15 years, treated for fissures, infractions, and fractures of the tibia were studied to elucidate the influence of age, type of fracture, and mechanism of trauma upon the course of union. In addition, an assessment was made of the possibilities the child has of correcting deformities of the diaphysis during continued growth. Eight-five of the children were followed up clinically and radiologically. The time taken for union to occur increased with increasing age. The "high energy" injuries were found to be more apt to cause transverse and comminuted fractures, with injury to the skin, than the "low energy" fractures. At the time of union, 25 patients had angular deformities. The mean correction of this deformity up to the time of follow-up was only 10 per cent. The tendency to correct the deformity ceased 18 months after the accident, and was independent of the child's age at the time of the accident.