Inverted papilloma of the nose and paranasal sinuses has been classified as a true neoplasm by most authors. Although these tumors are histologically benign, they tend to be act clinically in a malignant fashion. They are certainly characterized by the high recurrence after inadequate removal. The authors report 2 cases of the inverted papilloma which had been diagnosed as a nasal polyp for which an intranasal operation was performed. The polyp recurred and the total mass was removed at our E.N.T. department and proved to be an inverted papilloma by histologic examination.