Cine CT, with its very rapid imaging capabilities, was used to evaluate eight adult patients suspected of nonfixed upper airway obstruction. A method was developed for such imaging, which provides 10 images at each of 12 contiguous levels, extending from the soft palate through the extrathoracic trachea. These give a dynamic view of the airway during at least one full respiratory cycle and take about 6 sec to obtain. Results were compared with similar studies in 10 normal volunteers. Seven of the patients showed intermittent obstruction on cine CT, while the eighth was judged normal. All results agreed with subsequent further investigations or confirmed clinical diagnoses. The pathology demonstrated included chondromalacia, laryngeal spasm, and polychondritis. Four patients were evaluated for sleep apnea. All showed dynamic abnormalities of the airway, although they were studied awake and asymptomatic, during normal quiet respiration. All were subsequently shown to have severe sleep apnea. We conclude that cine CT has the potential to provide information quickly and noninvasively on upper airway dynamics and has certain definite advantages over conventional studies.