The effectiveness and safety of 200 micrograms/day of intranasal flunisolide in the treatment of perennial rhinitis was studied in 56 patients in a 6 wk double-blind parallel vehicle controlled clinical trial. In addition, patients failing to respond to placebo were entered into a 6 wk open trial with the active drug. Forty-six percent of the flunisolide-treated patients achieved total or substantial control of their nasal symptoms compared to 11% of the placebo-treated group in the double-blind study (p = 0.031). Eighty percent of patients achieved total or substantial control of their nasal symptoms in the 6 wk open study. No adverse effects attributable to flunisolide were observed. Parameters of IgE-mediated reactivity, including immediate-type skin test reactivity, total serum and nasal secretion IgE, specific serum and nasal secretion IgE, and nasal eosinophilia, were also assessed in these patients. Although benefit from flunisolide significantly correlated with all of these parameters except specific serum IgE, the absence of these findings did not preclude significant benefit from the drug. This study demonstrates the efficacy and safety of intranasal flunisolide in the treatment of perennial rhinitis, especially but not exclusively in those patients with evidence of IgE-mediated reactivity.