The purpose of this study was to determine whether nasal inflammation is present in patients with obstructive sleep apnea (OSA). The number of polymorphonuclear leukocytes (PMNs) and the concentrations of bradykinin and vasoactive intestinal peptide (VIP) were quantified in nasal lavage fluid of eight nonsmoking patients with OSA and in six matched controls before sleep and the next morning. The total number of cells and the percentage of PMNs was significantly higher in patients with OSA in comparison to controls before and after sleep (P < .05). Likewise, bradykinin and VIP concentrations were significantly higher in patients with OSA in comparison to controls before and after sleep (P < .05). These findings indicate that nasal inflammation is present in patients with OSA. We suggest that nasal inflammation plays a role in upper airway obstruction in OSA.