Topical steroids are known to be effective in allergic inflammatory airway diseases. However, progress in the treatment of these diseases has also called for the use of unadulterated drugs, without lubricants and preservatives. Rhinocort Turbuhaler, a multi-dose inhaler containing budesonide as a pure powder, is a newly developed device without any carrier gas, preservatives or lubricants. The efficacy and tolerance of this product were evaluated in 60 patients with birch pollen rhinitis. After a run-in period of 1 week the patients received once daily for 4 weeks either budesonide pure powder (400 micrograms) or placebo in a double-blind randomized fashion. Assessment of efficacy was made by comparing scores for different nasal and eye symptoms. The additional use of antihistamine tablets was assessed. In 22 of the patients nasal peak inspiratory flow rate was measured before and after 1 week of treatment. Budesonide was significantly more effective than placebo in controlling the nasal symptoms (P-values ranging from 0.011-0.045). The use of antihistamine tablets was significantly lower in the budesonide group (P = 0.012). The nasal inspiratory flow rate was increased after 1 week of treatment in the budesonide treated group of patients as compared with placebo (P = 0.007). No differences were observed between the groups with regard to eye symptoms or adverse effects. The results show that budesonide delivered from a dry powder inhaler is an effective and well tolerated treatment of seasonal allergic rhinitis.