Myelodysplastic syndrome (MDS) represents a heterogeneous group of potentially malignant diseases of bone-marrow stem cells. Acute myelogenous leukaemia (AML) is an inevitable outcome for many patients with MDS. Azacitidine has been reported to result in comparably higher response rates and improved survival than other treatment strategies. In this retrospective study, we report the results on 25 real life patients with MDS, CMML or AML treated with azacitidine between 2005 and 2009. All patients fulfilled the World Health Organization criteria for MDS and AML. No eligibility criteria other than diagnosis were considered. Complete response (CR) rate was observed in three of the 25 real life patients (12%) with a median duration of CR of 5 months (46 months). Seven patients (28%) had mono- or bi-lineage haematologic improvement and 15 patients (60%) showed neither morphologic nor haematologic response. Among 17 non-AML patients, the median time from onset of Aza-C treatment to AML transformation was 10 months (415 months). Overall death rate was 72%. All of the eight AML patients died. The death rate under Aza-C among non-AML patients was 59%. Unlike the results of the clinical trials, our data show that Aza-C has a limited activity in real-life patients with MDS and AML. It is obvious that Aza-C can induce complete or partial responses in a considerable number of MDS patients but responses are usually not durable as we observed in our patients. Copyright (C) 2011 John Wiley & Sons, Ltd.