Purpose: The purpose of this study is to evaluate the difference between open reduction and internal fixation (ORIF) and intermaxillary fixation (IMF) of mandibular fractures. Methods: A total of one hundred twenty-seven patients who were treated for mandibular fractures at Chosun University Dental Hospital, from January 2008 to December 2010, and analyzed their prognoses based on the use of IMF at the time of fracture reduction. The patients were divided into two groups; the manual reduction group without IMF and IMF group. Results: After reduction of the mandibular fracture, good results were obtained with majority patients. Nonetheless, seven patients (13.0%) in manual reduction method without arch bars or IMF, developed complications after surgery. Three patients underwent IMF due to occlusal instability after surgery, while one patient underwent re-operation. Thus, a significant difference was not observed between the IMF and manual reduction groups. Conclusion: Manual reduction and IMF at mandibular simple fracture could produce good results. In case of mandibular simple fracture, it was recommended with only manual reduction without IMF or IMF during a short period.