The BCR/ABL-negative myeloproliferative neoplasms (MPNs) of essential thrombocythemia, polycythemia vera, and primary myelofibrosis, over the natural course of their disease, have an increasing predisposition to transform to overt acute myeloid leukemia (AML)-most appropriately referred to as MPN-blast phase (MPN-BP). Although this transformation is a rare event, once AML has occurred, it is associated with a poor response to therapy and short survival. The molecular events leading to transformation are poorly defined. Currently, no therapy other than allogeneic stem cell transplantation (ASCT) has been demonstrated to alter the natural history of this disease. Multiple therapeutic investigations are currently ongoing, including early ASCT, hypomethylating agents, and JAK2 inhibition, to try to alter the course of the disease and improve outcomes. This review focuses on the latest advances in our understanding of the biology of leukemic transformation and current clinical therapies that are available for this patient population.