The orthopaedic surgeon experiences the difficulties of treating segmental tibial fractures by internal fixation and accompanying complications. OBJECT : The purpose of this study has been to review the useful treatment of 21 interlocking nails in the tibial segmental fracture, to investigate the union rate related to fracture types and to analyze the complications related to it. METERIAL and METHOD : Between November 1988 and August 1995, the authors treated tibial segmental fractures with interlocking intramedullary nail and analyzed 21 cases with followed up of more than 1 year. Injury mechanism were caused by traffic accident in which high velocity accounted for 17 cases. 11 cases of segmental tibial fracture were closed, and 10 cases were open. 6 cases of open fracture were open type 1, and 4 cases were open type II. We treated 21 fractures with unlearned intramedullary nail of 7 cases and limited reamed intramedullary nail of 14 cases. RESULT : Callus formation and consolidation were faster at the posterolateral aspect of the tibia than in anteromedial aspect. Radiologically complete union was faster in proximal portion at average 26.8 weeks than distal portion of segmental fracture at average 35.6 weeks. Complications included 2 cases of nonunion, 1 infection, 2 screw breakage and 2 ankle joint stiffness. CONCLUSION : We achieved excellent results using interlocking intramedullary nail by limited reaming or unlearned methoo in the tibial segmental fracture even though the injury was caused by high-velocity external force.