The myelodysplastic syndromes (MDS) consist of a heterogeneous spectrum of myeloid clonal hemopathies. The Revised International Prognostic Scoring System (IPSS-R) provides a recently refined method for clinically evaluating the prognosis of patients with MDS. Molecular profiling has recently generated extensive data describing critical hematopoietic molecular and biologic derangements contributing to clinical phenotypes. Current molecular insights have demonstrated roles of specific somatic gene mutations in the development and clinical outcomes of MDS, including their propensity to progress to more aggressive stages, such as acute myeloid leukemia. This article focuses on these recently reported clinical and underlying pathogenetic findings. The discussion provides a synthesis of the prognostic clinical, molecular, and biologic abnormalities intrinsic to the aberrant marrow hematopoietic and microenvironmental influences in MDS.