Introduction: Hypomethylating agents have become a standard therapy for certain myeloid malignancies.Aim: The aim of this preliminary study was to assess efficacy and safety of azacitidine in patients with myelodysplas tic syndromes (MDS), chronic myelomonocytic leukemia with 10-29% blasts (CMML-2) and acute myeloid leukemia (AML) treated in a single center.Material and Methods: Twenty-six (69% male and 31% female, median age 67.8 years) patients (MDS, = 15; CMML-2, n = 2; AML, n = 9) treated with azacytidine in the period April 2017 to October 2018 year were included in the study. Disease assessment was performed after the 3rd cycle, 6th cycle, and at progression.Results: The median number of administered cycles was 6 (1-16). Erythroid response was achieved in 46.7% after 3rd cycle and 66.7% after 6th cycle. Platelet response was reached in 72.7% after 3rd cycle and 40% after 6th cycle and neutrophil hematological improvement in 27.3% and 50%, respectively. Only one patient (8.3%) progressed after the 6th cycle, stable disease or better marrow response was achieved in the others. The median progression free survival (PFS) and overall survival (OS) were 7.9 and 10.7 months in the MDS group and 9.7 and 11.5 months in the AML group, respectively. None of the patients with CMML-2 progressed at the end of the study. The only found factor to correlate with shortened PFS and OS was IPSS high risk MDS. The most frequent grade ≥ 3 adverse events was neutropenia 38.5%, followed by anemia 15.4% and thrombocytopenia 11.5%.Conclusion: The therapy with azacitidine is an option for elderly patients with high-risk MDS, AML and CMML-2 that provides PFS and OS for approximately one year irrespective of age or nosological subgroup. These are preliminary data and larger patient cohort and longer follow-up period are needed for clinical conclusions.