Mucor is an opportunistic mold that causes mucormycosis. At least 50% of reported cases are associated with uncontrolled diabetes, and many of the remaining patients are immuno- suppressed. It appears as black crusting in the nose and sinuses and spreads rapidly to involve the cerebrum. Biopsy reveals nonseptate hyphae, which confirms the diagnosis. Treatment is directed toward control for diabetic ketoacidosis and use of amphotericin B.