A detailed cephalometric analysis was conducted on lateral x-rays from 30 adult patients with obstructive sleep apnea (OSA) and 12 age- and sex-matched controls. Statistical findings show that OSA patients are different from controls in at least five ways: 1. Their tongue and soft palate are significantly enlarged. 2. The hyoid bone is displaced inferiorly. 3. The mandible is normal in size and position (no micrognathia or malocclusion), but the face is elongated by an inferior displacement of the mandibular body. 4. The maxilla is retropositioned and the hard palate elongated. 5. The nasopharynx is normal, but the oropharyngeal and hypopharyngeal airway is reduced in area by an average of 25%, a factor that could produce or enhance OSA symptoms. These data suggest that cephalometric evaluation could be useful when used with head and neck examination, polysomnographic and endoscopic studies to evaluate OSA patients, and to assist with the planning/surgical treatment for improvement of upper airway patency.