Experimental evidence suggests that anthracyclines, widely used in cancer chemotherapy, may impair kidney function. We assessed kidney function by serum creatinine, urinary N-acetyl-beta-D-glucosaminidase activity indices (NAGi) and microalbuminuria (MA) in 160 serum and urine samples obtained from 66 children with cancer. The effect of dexrazoxane was analyzed in 6 children on dexrazoxane supportive therapy in conjunction with daunorubicin (DNR) treatment, as compared with 6 children not receiving this agent. NAGi was significantly (p<0.05) elevated after treatment by DNR, doxorubicin, epirubicin (EPI) and idarubicin (IDA). MA proved to be a less sensitive indicator of kidney damage than NAGi. DNR resulted in a progressive deterioration of proximal tubular function as determined by linear regression analysis. The mean NAGi in the dexrazoxanetreated group was significantly (p<0.005) lower than in children not receiving dexrazoxane prior to DNR treatment. In conclusion, our study demonstrated that DNR, EPI and IDA induced an acute renal tubular damage similar to known tubulotoxic agents as cisplatin, carboplatin, cyclophosphamide and ifosfamide. The damage was clinically mild and only a minor proportion of patients can be expected to develop long-lasting tubulopathy with negative impact on the quality of life.