Sinonasal mucormycosis is a rare, life-threatening and insidious fungal infection. Uncontrolled diabetes mellitus and immunsupression are the most important risk factors. The infection is clinically characterized by black necrotic tissues and crusting in the nasal cavity. In acute fulminant rhinosinusitis and particularly in infections caused by mucor species, black scar tissues seen on the nasal mucosa are pathognomonic. High level of suspicion in the risk group the diagnosis is confirmed by histopathological examination. The rhinoorbital form is even rarer and the findings may range from orbital pain to ophtalmoplegia and blindness. In this report we present a 72-year-old female patient with uncontrolled type 2 diabetes mellitus who was admited with the complaints of exophtalmos in the left eye, diplopia and headache. In the physical examination there was purulent discharge in the middle meatus and left orbital abscess was detected on computed tomography. We performed an emergency endoscopic sinus surgery. While we did not observe any necrotic tissues, granulation tissues were detected and pus was drained from the orbital cavity. The result of the histopathological examination was reported as invasive mucormycosis. We presented this case to emphasize the importance of early diagnosis and treatment of rhinoorbital mucormycosis.