We studied the clinical and immunological effects of three months' treatment with intranasal flunisolide (100 micrograms daily) in 18 allergic patients with perennial rhinitis. 17 were hypersensitive to house dust mite and one to Parietaria pollen only. We found no significant changes in white blood cell count, serum levels of IgE and nasal IgA. However the treatment induced a marked improvement of clinical symptoms in all cases, and we observed a significant reduction of total IgE in nasal secretion. Flunisolide seems to exert this effect through its antiinflammatory action on the nasal mucosa.