During 4 weeks of the grass pollen season in the south of Sweden 27 patients with seasonal allergic rhinitis were treated topically with a beta-adrenoceptor stimulant, KWD 2131, which in an earlier rhinomanometric study had shown a prophylactic effect at nasal allergen provocations in hay-fever patients. A clinical effect of KWD 2131 could not be documented in this randomized placebo-controlled, double-blind comparative study. The results contribute to conclusions in the clinical implications of rhinomanometric data.