The present work shows 13 cases of inverted papillomas of the nasal fossae treated at the Fundación Jiménez Díaz from 1954 to 1992. Four of them were found in the lateral wall of the nose, one in the nasal septum and the other one in the frontal sinus. The latter coexisted with a transient carcinoma. One of them suffered a secondary malignant process. This paper discusses the etiology of these tumors, their histology, clinical features, radiological aspects, trend to relapse or malignancy, as well as the most effective treatment in the authors' opinion.