Mucormycosis is a rare infection that occurs in immunocompromised patients. The rhinocerebral form presents in diabetics as a severe necrotizing sinusitis and is not frequent in patients with haematologic malignancies. Diagnosis requires direct examination and culture of biopsy specimens. Two patients with rhinocerebral mucormycosis and haematologic neoplasms (Non-Hodgkin's lymphoma and acute myeloblastic leukaemia) are described. Both patients had severe drug-induced neutropenia when the infection appeared. One patient died in spite of aggressive treatment with surgery and amphotericin.