The paranasal sinus infections caused by Aspergillus spp. are usually presented clinically with mild symptoms, however they may lead to invasive disease and mortality especially in immunocompromised individuals. In this report a fatal case of sino-orbital aspergillosis developed in an immunocompetent patient has been presented. Seventy-four years old female patient was admitted to the hospital with the complaints of fever and progressively increasing headache that continued for 15 days. Due to the development of nausea, vomiting, loss of consciousness and stiff neck in the following days, cerebrospinal fluid (CSF) sample was obtained. Direct microscopic examination of the Gram and acidfast staining of the CSF sample revealed no microorganisms, no growth was detected in CSF culture and PCR amplification was negative for Herpes simplex virus and Mycobacterium tuberculosis. Since no response was achieved by empirical ceftriaxone, ampicillin and conventional anti-tuberculosis treatment and tachypnea, proptosis and progressive respiratory failure developed in the patient, she was transferred to the intensive care unit. The radiological examination revealed soft tissue lesion filling the sphenoid sinus, extending to the nasal cavity and suprasellar cistern, destruction of bones, dilated orbital vein, cavernous sinus thrombosis and infarction on left cerebral peduncule. Patient was operated and pus and fungus ball were aspirated from the openings of both sphenoid sinuses. Gomori methenamine silver, periodic acid-Schiff and haematoxylin-eosine staining of the operational material exhibited dichotomously branching hyphae. The patient was diagnosed as invasive sino-orbital aspergillosis based on the clinical, radiological and histopathological findings. Despite antifungal therapy and surgical debridement, the patient died. It should always be kept in mind that aspergillosis can develop in immuncompetent individuals. Delay in diagnosis and treatment may lead to fatality. Thus multidiciplinary approach is necessary for early diagnosis and successful treatment of aspergillus infections.