Myelodysplastic syndrome (MDS) is a hematological disorder characterized by ineffective hematopoiesis. The only known curative treatment for patients with MDS is allogeneic stem cell transplantation. However, only a minority of patients are candidates for this aggressive therapy. DNA hypomethylation agents have been shown to have activity in this disorder and are postulated to work by reversing this epigenetic mechanism of gene-silencing. Recently, 5-azacitidine, administered subcutaneously for seven days, received approval by the FDA for the therapy of MDS based on a randomized trial which demonstrated a diminished risk of leukemic transformation and improved survival when compared to best supportive care.