There is lack of systematic reports of MR imaging characteristics of angioinvasive fungal ear infections. We present a case of angioinvasive necrotizing fungal otomastoiditis in which a confident prospective diagnosis was made on the basis of highly characteristic MRI features of coagulative tissue necrosis. The MR findings prompted urgent surgical debridement and systemic antifungal treatment in a 56-year-old neutropenic patient undergoing chemotherapy for acute myelogenous leukemia.