Two cases of fulminant hyperpyrexia induced by cytotoxic agents (bleomycin in a patient with lymphoma, and daunorubicin in a patient with acute myeloblastic leukemia) are presented. Each patient had a fever greater than 42 degrees C, with a shock-like reaction and coma. Evidence of disseminated intravascular coagulopathy developed in the patient with bleomycin-induced hyperpyrexia and she died 24 hours afterwards. The pathogenesis and management of hyperpyrexial reactions to cytotoxic drugs are discussed.