INTRODUCTION: In a surgery of the oral cavity, nasotracheal intubation is often carried out to secure the surgical field. By passing a tracheal tube through the nasal cavity to the pharynx, the nasotracheal intubation can lead to complications that do not occur with oral intubation, such as nasal bleeding and submucosal aberration etc. The purpose of this study is to examine the method of CT evaluation and pretreatment for a safe nasotracheal intubation. MATERIALS AND METHODS: Among 30 patients who orthognathic surgery was performed at Chung-Ang University Hospital during the period August 2009 to October 2009, 30 patients were included. RESULTS: CT evaluation with pretreatment group had a significantly lower incidence of nasal bleeding than the group with no pretreatment. CONCLUSION: CT evaluation with pretreatment helps to minimize nasal bleeding during nasotracheal intubation.