During cytostatic combination treatment with five different anti-tumor agents two female patients suffered from cardiac failure which proved fatal. This was mainly due to doxorubicine (adriamycin) and daunorubicine. In an 8-year-old patient the cumulative dose was reached after 14 months of treatment (total dose of adriamycin 420 mg/m2, of daunorubicine 280 mg/m2) and in a 7-year-old patient after 16 months (total dose of adriamycin 480 mg/m2, of daunorubicine 280 mg/m2). Cardiac failure which occurred 12 months after the onset of treatment in a 12-year-old girl (total dose of adriamycin 310 mg/m2 and of daunorubicine 280 mg/m2) could be brought under control. The cumulative dose of adriamycin should be limited to 500 mg/m2 in children without risk factors.