We present the case of a 44 year-old patient with chronic sinusitis who developed left exophthalmos and purulent nasal discharge. Mycological studies from the nasal sinuses revealed dichotornous hyphae characteristic of Aspergillus. Later on, a histopathologic study revealed and anaplasic neoplasm of left maxilar sinus. Treatment for the mycosis was started promptly with Amphotericin B, Itraconazole and Rifampin but no cure was obtained and the patient died 40 days later. Aspergillosis of paranasal sinuses is a rare, oportunistic mycosis, usually fatal if it invades the orbit and the cranial cavity.