Cinefluoroscopic findings are described in nine children with sleep-related upper airway obstruction who are asymptomatic while awake. Asleep, these patients show strikingly similar changes in the region of the hypopharynx. During inspiration, the tongue and hypopharyngeal soft tissues are approximate, obliterating the hypopharyngeal air space causing intermittent and almost complete obstruction to air flow. The value of cinefluoroscopic studies on sleeping children with clinical symptoms of airway obstruction during sleep is emphasized.