The presented study compares the efficacy and the toxicity of idarubicine and mitoxantrone in combination with cytosar (3 + 7) in induction treatment of the patients with AML aged 55-75. 31 patients at the age of 55-75 (median 62) were evaluated in the arm with idarubicine and 29 patients at the age of 57-74 (median 64) in the arm with mithoxantrone. Complete haematological remission was achieved in 13 patients (41.9%) in the arm with idarubicine and 15 patients (51.7%) in the arm with mitoxantrone. The medians of overall survival time (OS) and disease free survival time (DFS) were 22 and 44 weeks in the idarubicine arm and 35 and 40 weeks in the mitoxantrone arm, respectively. Statistical analysis did not prove any significant difference in the complete remission rates, in the number of deaths during cytopenia, in the OS or DFS, in the duration of hospitalisation, severe neutropenia and thrombopenia, in the number of days with febrile neutropenia, or in the consumption of platelets and erythrocytes transfusion units between both arms. Despite the fact that these results are not statistically significant in favour of any treatment arm, which is probably influenced also by the small number of evaluated patients, more favourable results were achieved in the arm with mithoxantrone with the respect to the evaluated parameters. From the point of view of cost-effectiveness, the difference could be observed when considering the price of both intercalating cytostatics. The use of mitoxantrone (Refador, Lachema) is 15x times cheaper per course of treatment than the use of idarubicine (Zavedos, Pharmacia). Autologous peripheral blood stem cells transplantation (APBSC) was carried out only in 4 patients younger than 60. No one of them was cured by APBSC but the median of OS of these patients was longer than the median in the other patients of the group. The results achieved are comparable with those of other trials conducted by various foreign groups. The possible causes of our unfavourable treatment results in this high-risk category of aged patients and the ways how to individualize the treatment with the use of prognostic factors analysis and how to improve the quality of life of the patients has been discussed.