Topical corticosteroids are the therapy of choice for nonallergic, noninfectious perennial rhinitis (NANIPER). However, the efficacy of steroid therapy in NANIPER is controversial, as is its mode of action. To our surprise, of 300 patients initially diagnosed as having NANIPER, only 65 reached threshold nasal symptom scores. Patients were randomized into four different treatment regimens: placebo administered twice daily (BD) for 8 weeks, fluticasone propionate aqueous nasal spray (FPANS) (200 microg) once daily (OD) and placebo OD for 8 weeks, FPANS (200 microg) OD and placebo OD for 4 weeks followed by FPANS (200 microg) BD for 4 weeks, and FPANS (200 microg) BD for 8 weeks. A small decrease in nasal symptoms was found, which only reached significance for sneezing in the FPANS 200 microg BD group. A significant dose-dependent decrease in immunocompetent cells was found in nasal biopsy specimens obtained before, after 4 weeks, and after 8 weeks of treatment. We conclude that FPANS did not significantly reduce nasal symptoms in this group of selected NANIPER patients, even though a significant effect on cells in the nasal mucosa was seen.