A randomized, double-blind, placebo-controlled, parallel group study was conducted in 11 centers to evaluate the safety and efficacy of a once-a-day regimen of 110 micrograms, 220 micrograms; and 440 micrograms of triamcinolone acetonide intranasal aerosol versus placebo in relieving the symptoms of rhinitis in 305 adult and older pediatric patients with perennial allergic rhinitis. Nasal stuffiness, nasal discharge, sneezing, nasal itching and the nasal index (the sum of the mean scores of the first three symptoms) averaged over the first 6 weeks and second 6 weeks of the study were significantly reduced in patients who received the 220 micrograms/day and the 440 micrograms/day dosages. The 110 micrograms/day group had a reduction in these nasal symptoms, but only the sneezing and nasal index were significantly (P less than .05) better than placebo. During the last 6 weeks of the study, patients were allowed to take oral back-up medication for their nasal symptoms; all three groups receiving triamcinolone nasal aerosol took less back-up medication than did the placebo group. There were no significant adverse effects or laboratory abnormalities noted during this study. Intranasal triamcinolone acetonide 220 micrograms and 440 micrograms, used once-a-day for 12 weeks is clinically and statistically superior to placebo for the treatment of perennial allergic rhinitis.