The effects of flutropium on histamine (Hist)-induced increase in intranasal pressure in non-sensitized guinea pigs and nasal mucosa capillary permeability in passively sensitized guinea pigs were investigated. Flutropium (0.3%), atropine (0.3%), diphenhydramine (0.01%) and cimetidine (0.1%) were directly inhaled into the nasal cavities by an ultrasonic nebulizer for 20 min, followed by inhalation of Hist (0.1%) for 10 min. Flutropium, atropine and diphenhydramine had an inhibitory action on the Hist-induced increase in intranasal pressure in guinea pigs. Cimetidine had no effect on this system. In passively sensitized guinea pigs (the challenge was performed 48 hr after sensitization), a 0.1-1.0 mg/kg injection of flutropium (i.v.) dose-dependently inhibited the allergic nasal mucosa capillary permeability. Atropine (10 mg/kg, i.v.) had no inhibitory action on this system. These results suggest that inhalation into the nasal cavities and i.v. injection of flutropium are effective in experimental models of drug- and allergy-induced rhinitis of the guinea pig.