Immunoglobulin E-mediated allergy generally has not been considered to be important in the pathogenesis of nasal polyps, despite elevated immunoglobulin E in polyp exudates, tissue eosinophilia, and degranulated mast cells. In previous reports, patients with nasal polyps were more likely to have positive skin tests to perennial than to seasonal allergens. It is postulated that nasal polyps result from the constant nature of perennial allergen exposure. The objective of this report is to compare the prevalence of sensitization to six aeroallergens in a group of nasal polyp (NP) patients, a group of allergic rhinitis (AR) patients, and those subjects with positive skin tests in the National Health and Nutrition Examination Survey (NHANES) II. Twenty-five consecutive NP patients evaluated over a 3-month period of time at Northwestern Allergy and Immunology Outpatient Center, in addition to 50 of the allergic rhinitis patients evaluated over the same time, were chosen randomly. All were skin tested with the following antigens: dog, cat, dust mite, grass, tree, and ragweed. Published skin test data from the NHANES II study of 14,367 individuals was obtained also. The percent of NP patients, AR patients, and NHANES II subjects with sensitization to perennial allergens was 72, 96, and 7.6%, respectively. The difference between the AR and NP patients was statistically significant (p = 0.006). The percent of NP, AR, and NHANES II subjects sensitized to seasonal allergens was 84, 86, and 17.7%, respectively. No statistical significance existed between the AR and NP patients, regarding seasonal allergens. Although the AR and NP had similar levels of reactivity to perennial and seasonal allergens, the NHANES II group was more than twice as likely to be sensitized to a seasonal allergen. The NP and AR groups were similar in prevalence of reactivity to seasonal allergens, but the NP patients in our population actually were less likely to be sensitized to perennial allergens than individuals with AR.