Mucormycosis refers to the disease caused by a growing number of members of the Mucorales. Typically an airborne infection, primary disease is initiated in the upper or lower airways and is associated with the clinical development of sinusitis, rhinocerebral mucormycosis, or pulmonary infection. Dissemination of infection to skin, brain, and other sites is less common, but direct extension of the infection to contiguous sites is common if patients do not receive aggressive surgical and medical therapy. Risk factors for the development of mucormycosis include diabetic ketoacidosis; neutropenia; protein-calorie malnutrition; and iron overload, with or without the concomitant use of deferoxamine. This last association has only recently been recognized and has emerged as a major life-threatening complication for patients who are undergoing hemodialysis. Intravenous drug abusers may inject spores of Mucorales with their drugs and may present with space-occupying lesions of the CNS. The underlying immunologic defects that are responsible for predisposing different populations of patients to the development of mucormycosis are not well understood, and there is no unifying theory to explain why most individuals have innate immunity to this group of fungi. Patients with mucormycosis who are managed aggressively (i.e., those who undergo surgical debridement and who receive therapy with iv amphotericin B) may have increased rates of survival. The role of new azole derivatives in the treatment of mucormycosis is unknown.