The role of infection as cause or effect in nasal polyps is debated. In experimentally induced sinusitis in rabbits, polyps are frequent. The initial polyp formation sequence involves multiple epithelial disruptions with proliferating granulation tissue. Regenerating epithelial branches spread into the underlying connective tissue, where intraepithelial microcavities give rise to a polyp body from the adjacent mucosa. Clinical as well as experimental studies indicate that nasal polyp formation and growth are activated and perpetuated by an integrated process of mucosal epithelium, matrix, and inflammatory cells, which in turn may be initiated by both infectious and noninfectious inflammation. The complexity of the pathophysiologic events in nasal polyposis is reinforced by the finding that epithelial desquamation, combined with infection or inflammation, will initiate polyp formation. Systemic glucocorticosteroids inhibit polyp formation as well as growth of pathogenic bacteria in the sinuses of rabbits with experimental infection. Therapeutic use of corticosteroids in polyp disease, combined with antibiotics or surgery, should be modified in relation to long-term progression, intensity variations, and predisposing conditions.