목적: Orthognathic surgery has been used to be the traditional treatment of choice for correcting type III malocclusion and several authors have asserted that bimaxillary surgery cause a relative narrowing of the upper airway that could trigger obstructive sleep apnea (OSA). However, its potential role in OSA development is still debated. This study aimed to ascertain the prevalence of snoring or OSA in malocclusion patients with bimaxillary surgery and to analyze the sleep architectures after surgery. 방법:Twenty two patients with Le Fort I and mandibular setback for type III malocclusion from Jan to Dec 2014 at Chung-Ang University Hospital participated and prospective study was performed. All patients underwent a physical examination, Epworth Sleepiness Scale evaluation, cephalometry, and watch PAT twice, 1 month prior to and 3 months after surgery. 결과:The patient population consisted of 5 males and 17 females. The mean body mass index was 22.5 kg/m2 and the mean age was 22.1 years. No patients complained of sleep-related symptoms and the results of watch-PAT showed normal values. Interestingly, total 3 patients (13%) were newly diagnosed with OSA and 6 patients (27%) complained of snoring subjectively after bimaxillary surgery. Watch PAT showed that two subjects were mild OSA and one was moderate. In addition, mean threshold of snoring dB was considerably elevated in 6 patients and mean dB was 24.2 dB before surgery and 42.8 dB at 3 months after surgery. Lowest oxygen saturation and valid sleep time were not changed after surgery in all patients. According to cephalometry and 3D CT results, we found that retropalatal area was significantly narrowed after surgery in patients with newly developed snoring and sleep apnea 결론:Our results showed that 13% showed newly diagnosed OSA and 27% complained of snoring after bimaxillary surgery for type III malocclusion. We need to provide this information to dentists and suggest an additional sleep study after surgery.