Objective To explore the clinical efficacy of secondary unreamed intramedullary nailing following primary external fixation for open tibial shaft fractures.Methods From March 2011 to June 2014,we treated 28 open tibial shaft fractures.They were 17 men and 11 women,aged from 21 to 62 years (average,38.2 years).After thorough debridement,the tibia was stabilized temporarily with external fixation.The wounds were handled with primary closure or secondary repair with skin grafts or tissue flaps.After the wounds healed,the external fixation was replaced by unreamed intramedullary nailing.Fracture union and complications were documented.The clinical efficacy was evaluated at the final follow-ups according to the Johner-Wruhs scoring system.Results All the 28 patients were followed up for 12 to 18 months (average,13.5 months).Bony union was achieved in all after 4 to 15 months (average,4.9 months).Delayed union was observed in 4 cases which were healed after dynamic fixation.There was no deep infection,nail breakage,malunion or limb shortening in any one.Mild knee pain was reported by 5 cases after surgery.According to the Johner-Wruhs criteria,18 cases were excellent,7 good,and 3 moderate,giving an excellent to good rate of 89.3％.Conclusion Primary external fixation and secondary unreamed intramedullary nailing can result in good fracture union with satisfactory biomechanical stability and favorable early rehabilitation in the treatmeut of open tibial shaft fractures.