We reviewed the results of the treatment of 23 tibial shaft fractures in 22 patients by primary unlearned locked intramedullary nailing. The duration of follow-up was average 10.1 months (range, from 6 to 27 months). The results were as follows : 1. There were 11 open and 12 closed fractures. 2. All fractures united clinically in an average time of 17.9 weeks(range 10 to 26 weeks), and radiologically in an average time of 19.4 weeks (range, 10 to 31 weeks). 3. Complications included 1(4.3%) case with delayed union and 3(13.0%) cases with malunion. 4. No patient had deep infection and there were no broken nails or screws in this series. 5. No fracture refuired an additional procedure before union, such as dynamization or bone graft.