The myelodysplastic syndromes (MDS) are clonal bone marrow disorders that lead to underproduction of normal blood cells. The consequent cytopenias result in infections and bleeding complications. MDS transform to acute myeloid leukemia in one-third of patients. The number of diagnoses has exploded in the past decade as a result of increased recognition and understanding of the disease and the aging of the population. New therapies can extend life. MDS are now considered the most common form of leukemia, and in some cases deserve immediate intervention. This review describes common presentations of MDS, optimal diagnostic approaches, and therapies for lower-and higher-risk disease.