The objective of this study was to compare the efficacy and safety of a pure powder formulation of budesonide, delivered from a new multi-dose dispenser for nasal drug application, with the commercially available budesonide pressurized aerosol, and with placebo. Of 116 patients with grass pollen-induced allergic rhinitis, 112 finished the study, which comprised a 4-week treatment period, preceded by a 1-week run-in period. The patients were randomized to four parallel treatment groups: budesonide powder 400 micrograms daily; budesonide powder 800 micrograms daily; budesonide aerosol 400 micrograms daily; and placebo powder. Treatment was given once daily in the morning. The study was double-blind regarding comparison between budesonide powder and placebo. Assessment of efficacy, made by comparing mean scores of nasal symptoms and use of rescue medication, showed equal efficacy of all three budesonide groups compared with placebo. There were no differences between budesonide-and placebo-treated groups with regard to side effects. Budesonide treatment had no demonstrable effect on the HPA-axis assessed by measurement of 24-h urine cortisol. We conclude that budesonide, delivered as pure powder from a multi-dose dispenser, is effective and safe for the treatment of seasonal allergic rhinitis. This new formulation is a good alternative to the commercially available preparations, as it does not contain carrier gas, preservatives or lubricants.