Myelodysplastic syndromes (MDS) are hematopoietic neoplasms characterized by an ineffective hematopoiesis associated with cytopenia(s), functional abnormalities of bone marrow lineages, morphologic dysplasia, and a progression to acute myeloid leukemia. The pathogenesis of MDS is exceedingly complex and involves the hematopoietic stem cells/hematopoietic precursors, bone marrow microenvironment, and complex interaction between these components. The diagnostic strategy in MDS has evolved significantly over the years from a strategy based almost exclusively on peripheral blood smear and bone marrow aspirate morphology to the integrated approach used in the 2001 and 2008 World Health Organization (WHO) classification schemes. In parallel with the diagnostic approach, evolution has occurred in the prognostic assessment and evaluation of treatment response. The prognostic assessment now includes both disease-related factors and patient-specific characteristics such as nonhematologic comorbidities. All these developments are particularly important considering the ever-increasing treatment options available for MDS. This review focuses on the diagnostic approach to MDS and highlights recent developments in the pathogenesis as well as select clinical advances. We present the overview of the minimal diagnostic criteria for a diagnosis of MDS, the WHO classification scheme, and briefly address the risk stratification.