Six new cases of mitomycin C (MMC)-induced hemolytic uremic syndrome are reported and the literature on renal-, pulmonary- and cardiotoxicity of the drug is reviewed. The number of reports concerning these side effects is still increasing. The incidence of all three side effects will be below 10%, while there appears to be a dose-dependency, with toxicity mainly occurring at cumulative doses of 20-30 mg/m2 or more. Toxicity often develops very sudden and the mortality rate especially of HUS is very high despite supportive care. The pathogenesis of toxicity is still unknown, although for HUS there are indications for a role of circulating immune complexes. The pulmonary toxicity can often be treated by corticosteroids, while the left ventricular cardiac failure can be treated with diuretics. The possible role of oxygen radicals in the development of MMC side effects is mentioned.