Nine acrocephalosyndactyly type I patients (Apert's syndrome) and three acrocephalosyndactyly type V patients (Pfeiffer's syndrome) were evaluated for the relative importance of upper and lower airway abnormalities in the generation of obstructive sleep apnea. All patients were found to have a combination of upper and lower abnormalities. The influence of lower pathology was greater in the infants, and the influence of upper airway, specifically pharyngeal, was greater in the adults. A comparison between preoperative and postoperative polysomnography revealed little improvement with standard craniofacial advancements. Furthermore, three patients are described who succumbed to pulmonary death despite tracheostomy. Conservative treatment with prone or lateral positioning and medical pulmonary regimens is advocated. Finally, the pathogenesis of this diffuse airway pathology is discussed.