We describe two patients with isolated cerebral mucormycosis and acquired immunodeficiency syndrome (AIDS). Their clinical course was rapid and fatal; early diagnosis and treatment with amphotericin B did not prevent a fatal outcome in both cases. Isolated cerebral mucormycosis has not (to our knowledge) been reported previously in patients with AIDS. Mucormycosis should be included in the differential diagnosis of central nervous system infections in intravenous drug abusers with AIDS. A brain biopsy is needed for the diagnosis of mucormycosis.