Abstract. The present study reviewed the records of 58 patients who underwent orthognathic surgery [sagittal split ramus osteotomy (SSRO), Le Fort I osteotomy, genioplasty, anterior maxillary alveolar osteotomy] between 2010 and 2015. To investigate the influence of preoperative oral health care on postoperative inflammation, infection and length of hospital stay in those patients, white blood cell (WBC) count and C-reactive protein (CRP) levels were compared between patients who received and did not receive preoperative oral care. The mean CRP level throughout the postoperative term was lower in the oral care group as compared to the non-oral care group. By contrast, the oral care group had a lower occurrence of postoperative infectious complications (surgical site infection, anastomotic leak) (13.6 vs. 20.8%) and a shorter average length of hospital stay (16.2±3.8 vs. 21.2±7.4 days). These results suggest that preoperative professional oral health care decreases the duration of hospital stay following orthognathic surgery by inhibiting inflammation and infectious complications during the postoperative stage.