PURPOSE: We report the surgical outcomes for femoral shaft fractures in polytrauma patients who were temporarily treated with external fixation and subsequently converted to internal fixation. METHODS: From August 2008 to April 2012, we enrolled 13 patients with multiple traumas due to high-energy injuries and concurrent femoral shaft fractures in which temporary external fixation was carried out. The mean age was 39 years, with a range from 18 to 55 years. Ten were men and 3 were women. According to the AO/OTA classification of fractures, type A was found in 5 patients, type B in 6, and type C in 2, with open fractures being found in 6 patients and femoral artery rupture occurring in 2. For internal fixation, intramedullary nailing was performed in 7 patients, and minimally-invasive fixation of locking compression plates was used in 6. RESULTS: Of the 7 patients converted to intramedullary nailing, 1 experienced delayed union. Of the 6 patients treated with minimally-invasive plate fixation, delayed union occurred in 5, and an auto-bone graft was performed within, on average, 8 months (range: 5~10 months), leading to bone union in all cases in the final follow-up. None of the patients experienced infections or complications involving other organs after having been converted to internal fixation. During the mean follow-up of 19 months, patients achieved satisfactory functional outcomes. CONCLUSION: In polytrauma patients with a femoral shaft fracture who have been treated with temporary external fixation and who may need internal fixation due to the occurrence of delayed union, an appropriate internal fixation method needs to be selected based on the patient's physical status, and the fracture type.