The cardiotoxicity of anthracycline antibiotics is a serious complication of anti-tumourous treatment. One of the possible ways how to prevent it or at least restrict it substantially is to use cardioprotective substances. The latter include ICRF-187 bispiperazinedione (dexrazoxan) which is manufactured and supplied by CHIRON Cop. under the name Cardioxane. The authors investigated by echocardiography indicators of systolic and diastolic function of the left ventricle in patients where cumulative doses of 180-240 mg/sq.m of doxorubicin were achieved. In 10 patients to whom Cardioxane was administered no changes of left ventricular function were recorded. In 18 patients treated with boluses of doxorubicin significant deterioration of left ventricular diastolic function developed. The authors provided evidence that relatively small cumulative doses of doxorubicin administered as boluses lead to impaired left ventricular diastolic function. These changes were not recorded in patients who were given the cardioprotective substance ICRF-187 (Cardioxane).