Myelodysplastic syndrome, a disorder of haematopoiesis, is associated with anaemia and an increased risk of infections, bleeding and the development of acute myeloid leukaemia. The disorder occurs mainly in later life. Until recently the only therapy that could induce sustained remission was allogeneic stem cell transplantation. However in elderly patients caution is needed with this therapy. Increasing awareness of the role of epigenetic changes in cancer development has led to the rediscovery of the cytidine analogues azacitidine and decitabine. At low doses these drugs inhibit DNA methylation. The efficacy of these drugs was demonstrated in the treatment of patients with myelodysplastic syndrome. These drugs showed low toxicity and were relatively well-tolerated in elderly patients. The results with azacitidine and decitabine have demonstrated that manipulation of the epigenetic process offers new antineoplastic treatment options.