Two groups of AML patients (n1 = 63, n2 = 20) and two groups of ALL patients (n1 = 33, n2 = 15) were treated using polychemotherapy protocols which in each leukaemia subtype differed mainly in adriblastin administration being either in bolus form (30 mg/m2/day i.v.) or fractional form at the beginning 20 mg i.v., then 6 mg/m2 every 6 h. The fractional method of administration was elaborated on experimental data indicating the superiority of continuous infusion of anthracyclines. In AML additional ara-C was given in continuous infusion only on 1 to 3 days, on 4 to 8 days duplicated dose was administered subcutaneously (i.e. 100 mg/m2 every 12 h). In patients given fractional doses of adriblastin and in AML also ara-C in the modified way the statistical analysis revealed a higher CR (ALL - 67%/93%, AML - 46%/60%) and CR + PR rates, a lower rate of infections as the cause of death in the AML group, lower rates of nausea and vomiting as well a lower increase of infections in the course of the induction treatment in the AML group. Another advantage was a lower total dose of adriblastin for remission induction treatment as well as an elevated cumulative dose which allows anthracyclines to be longer used. The efficacy of the modified ara-C administration confirms our earlier observation.