Background: The treatment of open tibial fractures is still an orthopaedic challenge and full of complications. In many cases the use of external fixator that has been known as a non-union machine is obligatory with a high incidence of pin track infection and other complications. The aim of this study was to compare the use of external fixation as a definite method for treatment of open tibial fractures with its subsequent conversion to internal fixation or casting. Methods: Sixty-seven young patients with type III open tibial fractures (Gustilo-Anderson classification) were treated with half pin external fixation. Twenty of them were converted into internal fixation after a period of 6-8 weeks. For another twenty-five, external fixator was removed and treatment continued with casting for a period lasting from 16 to 20 weeks. And for twenty two patients the fixator continued until complete union. The patients followed up for 10-16 months and were evaluated in terms of union time, union rate, infection, range of motion, malunion, non-union, nerve injury, and reduction. Results: There was a meaningful difference only in the union time and superficial infection between the first group and the other two groups. Conclusion: The conversion of external to internal fixation can be considered as a safe, effective, less complicated, and more acceptable method for the treatment of open tibial fractures.