We report a case in which tracheal stenosis was discovered during endotracheal intubation. A 19-year-old woman with Down syndrome was scheduled to undergo treatment of multiple dental caries under intubated general anesthesia. During the first general anesthetic, we felt some resistance while advancing the endotracheal tube through the trachea. Prior to a second general anesthetic 2 years later, we performed 3-dimensional computed tomography to evaluate the tracheal stenosis and devised a strategy that established an airway without advancing the endotracheal tube over the stenotic lesion. Careful attention is required when performing endotracheal intubation because patients with Down syndrome sometimes have tracheal stenosis.