Chronic myelomonocytic leukemia (CMML) is a disease typically of the elderly. It is suspected when monocytosis reaches 1000/microl. It may be associated with "B" symptoms (fever, sweating, and weight loss) but also visceral, skin and autoimmune complications. Current treatment strategies aim at reducing the symptoms and have no curative goals. In this context hypomethylating agents have shown a good efficacy. Allogeneic hematopoietic stem cell transplantation (HSCT) remains the only curative option but remains difficult to perform in elderly patients population, even if transplantation with a reduced intensity conditioning has reduced the risks. A new prognostic scoring helps to recognize the patients with poor prognosis and to better selected candidates for the HSCT.