Purpose: The purpose of this study was to evaluate the incidence of intra- and postoperative complications of orthognathic surgery and their relevance. Materials and Methods: The clinical records and X-rays of 418 patients who underwent surgery at Chosun University Dental Hospital, Korea, over a 12-year period between 1998 and 2009 were examined. Results: The followings are some of the most common complications which happened during the oper-ations: Inadequate osteotomy in 25 cases, excessive bleeding in 11 cases, nerve injuries in 6 cases, soft tis-sue injuries in 8 cases, and tooth injury, and insertion of foreign bodies in 4 cases respectively. The most frequent complications which happened after surgery are shown below. Paraesthesia in 262 cases, dyspnea in 78 cases, pain in cervical region in 49 cases, open bite in 14 cases, plus 62 cases where other complications occurred. Despite the great variety of complications, severe life threatening complication frequency seems to be extremely low. Conclusion: Orthognathic surgery appears to be a relatively safe procedure but complications related to orthognathic surgery do still occur. Accurate evaluation and precise surgery are needed to minimize complications.