Habitual snoring in adults may be related to upper airway dysfunction, although the precise relationship has never been studied. We quantitatively measured snoring and correlated it with upper airway properties in 50 apneic and 59 nonapneic adult male patients. Both groups were similar in terms of nasal airflow resistance and pulmonary function tests. We found a significant correlation between the severity of snoring and nasal airflow resistance in both groups, and between the severity of snoring and pharyngeal and glottic areas in the apneic group. We conclude that snoring may be associated with abnormalities in upper airway properties.