The introduction of nasal glucocorticosteroids, 30 years ago, has been the most important therapeutic progress in rhinitis management since the introduction of the first generation of antihistamines. Our knowledge of the mode of action of glucocorticosteroids in the nose has improved as the airway mucous membrane of the nose is easily accessible for investigation. However, the exact mechanism behind the marked clinical effect remains unclear. Topical glucocorticosteroids are highly effective in diseases characterized by eosinophil-dominated inflammation (allergic rhinitis, nasal polyposis), but not in diseases characterized by neutrophil-dominated inflammation (common cold, infectious rhinosinusitis). Experience for 30 years and a long series of controlled studies have shown that the treatment is highly effective and that the side effects are few and benign. Intranasal glucocorticosteroids can therefore be considered as first-line treatment for allergic and non-allergic, non-infectious rhinitis and nasal polyps.