Experimental studies on mitomycin-C nephrotoxicity are scanty and mention the occurrence of cortical hemorrhage, tubular necrosis, or hydronephrosis secondary to papillomatous hyperplasia of the uroepithelium. To our knowledge, only one experimental study has mentioned morphological lesions similar to the hemolytic uremic syndrome in the human. In the present study 40 female Wistar rats were studied following unilateral renal perfusion of the left kidney with 2 mg/kg of mitomycin-C. Renal lesions corresponded to cortical necrosis with the presence of large bizarre nuclei. The presence of these nuclear atypias supports a direct toxic effect (alkylation) of the mitomycin or its metabolites on cells.