A 44 year-old man with a type I Neurofibromatosis (NFI) and an intercostal mass is presented. By means of percutaneous fine needle aspiration punction under CT control, this tumor could be diagnosed of neurofibroma. It is important to remark not only the role of helical CT with anatomical reconstruction in the diagnosis of intercostal tumors, but also that intercostal location of neurofibromas has been rarely reported in the literature. Because of frequent association between NFI and neoplasms, it is always necessary to perform histological study of every new tumor that appears in the course of this entity.