A case of rhinocerebral mucormycosis occurring in a 41-year-old man with insulin-treated diabetes mellitus is reported. Microscopically, biopsy samples obtained from the left ethmoid and middle turbinate sinuses contained fungi that formed mycotic granulomas associated with multinucleate giant cell arteritis. The multinucleate giant cells contained broad, infrequently septate hyphase consistent with mucormycosis. The patient received surgical debridement with extenteration of the left orbit, and intravenous liposome-encapsulated amphotericin B. After 12 months, examination of the patient revealed complete healing. Multinucleate giant cell granulomas and arteritis are only exceptionally associated with rhinocerebral mucormycosis, but these histologic findings may be correlated with a progressive disease with better prognosis.