Allergy is generally believed to be an underlying cause of nasal polyps. The objective of this study was to define allergic nasal polyps. We investigated specific immunoglobulin E (sIgE) in polyp tissue. Thirty pieces of polyp tissue were taken from patients with positive allergic symptoms, and 30 from patients without allergic symptoms. Nasal polyp tissue homogenate and serum from these patients were prepared for detecting sIgE by a CAP method. For patients with allergic symptoms and/or positive serum CAP test results, the rates of positive tissue CAP tests were low: 36.7% and 35.7%, respectively. However, nearly all of the tissue CAP-positive subjects had allergic symptoms and positive serum CAP tests. We conclude that the local tissue sIgE profile reflects more specifically the allergic status of patients with nasal polyps than does the systemic serum test or the presentation of allergic symptoms. Thus, polyp tissue CAP tests might be performed in patients with positive allergic symptoms and positive serum CAP tests to define an allergy-induced polyp precisely. Then, specific antiallergic treatment could be administered to prevent polyp recurrence.