Background: Topical nasal corticosteroids are rapidly gaining acceptance as first-line therapy for seasonal allergic rhinitis, but there is a desire for effective corticosteroids with an improved safety profile over existing products.Objective: A multicenter, double-blind dose ranging study was conducted to compare the activity and tolerance of four doses of mometasone furoate nasal spray (tradename Nasonex) and placebo in adult patients with seasonal allergic rhinitis.Methods: Four hundred eighty patients with seasonal allergic rhinitis were enrolled and randomized to receive mometasone furoate nasal spray 50 mu g (n = 96), 100 mu g (n = 95), 200 mu g (n = 98) or 800 mu g (n = 95), or placebo vehicle (n = 95) once daily for 28 days.Results: All of the doses of mometasone furoate nasal spray showed activity in reducing the severity of rhinitis. The 200-mu g dose reduced total nasal symptom scores and total symptom scores throughout the study (P <.05 versus placebo vehicle). The 50-mu g dose and the 100-mu g dose showed less consistent activity at early timepoints (days 3 and 7), while the 800 mu g dose did not provide significant additional benefits over the 200-mu g dose. All dose levels were well tolerated.Conclusion: The results of this trial indicate that 200 mu g once daily is the optimum dose of mometasone furoate nasal spray for the treatment of seasonal allergic rhinitis.