Fibrosarcoma arising in the sinonasal cavities are very rare. By the time of clinical diagnosis, they are usually advanced. Lack of adequate surgical margins predisposes these patients to tumor recurrences. Most common sites are the extremities, with only one percent of fibrosarcoma arising in the head and neck area. The imaging features of these tumors reflect their aggressive behavior. We report the case of a maxillary sinus fibrosarcoma in a 16 year-old male patient. Neoadjuvant chemotherapy, medial maxillectomy, adjuvant chemotherapy and subsequent external irradiation was perfomed.