Malignant fibrous histiocytoma is a frequent neoplasm of the soft tissue occurring in patient aged between 5th and 7th decade. Maxillary sinus is an unusual site of origin and few cases have been described in literature. Because of the rarity and its aspecific clinical symptoms, diagnosis is troubled. Moreover, the association of an inflammatory process together with the difficulty to take a representative sample, the histopathological diagnosis is often problematic. The Authors report a case concerning a 30-years-old men treated at National Cancer Institute of Milan. Clinical history, biological behaviour, therapy and prognostic features of the tumor are discussed.