BACKGROUND : Mucormycosis is a group of rare but life threatening angioinvasive infections caused by fungi of the order Mucorales that often occurs in immunocompromised patients and individuals with poorly controlled diabetes. Rhinocerebral mucormycosis can mimic sinusitis but can rapidly progress to deeper disease and cause facial necrosis. Facial vascular thrombosis is a rare complication of mucormycosis and can confound diagnosis of the disease. METHODS : We report the case of a 25-year-old female with poorly controlled type 1 diabetes mellitus who initially presented with symptoms of sinusitis but rapidly progressed with signs of left-sided facial necrosis due to occlusion of the left internal maxillary artery. Early surgical debridement did not yield a microbiological diagnosis. Deeper surgical debridements ultimately revealed angioinvasive fungal disease consistent with mucormycosis. The patient recovered after repeated surgical intervention and aggressive parenteral antifungal therapy. CONCLUSIONS : This case illustrates an atypical complication of mucormycosis, and emphasizes that a high index of suspicion in vulnerable patient populations aids in the diagnosis of this life-threatening infection.