Pharyngeal airway during sleep was observed with help of Fibro-optic flexible bronchoscope and cineradiography in 10 adult patients with Hypersomnia Sleep-Apnea (HSA) syndrome. The results of the study suggest that the structures involved in production of airway obstruction in the patients with HSA syndrome are the muscles of velopharyngeal sphincter and tongue. The laryngeal airway was not obstructed during the episodes of apnea.