The molecular basis of chronic idiopathic myelofibrosis (CIMF) has remained elusive, thus hampering the development of effective targeted therapies. However, significant progress regarding the molecular mechanisms involved in the pathogenesis of this disease has been made in recent years that will likely provide ample opportunity for the investigation of novel therapeutic approaches. At the forefront of these advances is the discovery that 35%-55% of patients with CIMF harbor mutations in the Janus kinase 2 tyrosine kinase gene. Until very recently, the management of patients with CIMF involved the use of supportive measures, including growth factors, transfusions, or interferon, and the administration of cytoreductive agents, such as hydroxyurea and anagrelide. However, several trials have demonstrated the efficacy of antiangiogenic agents alone or in combination with corticosteroids. In addition, the use of reduced-intensity conditioning allogeneic stem cell transplantation has resulted in prolonged survival and lower transplant-related mortality. ©AlphaMed Press.