Myelodysplastic syndromes [MDS] are clonal disorders of hematopoietic stem cells leading to a deregulation of proliferation and differentiation of the bone marrow cells. Clinically the patients present with symptoms and signs of anemia, thrombocytopenia, and neutropenia. About a third of the patients will develop acute myeloid leukemia. Supportive care is the mainstay of therapy in these mostly elderly patients. G-CSF should only be given in cases of neutropenia and infection, but not prophylactically. Selected patients with severe or transfusion-dependent anemia will respond to treatment with erythropoietin. In advanced MDS aggressive chemotherapy should be considered, while in patients below 50 years of age and an HLA-identical sibling donor allogeneic bone marrow transplantation is the treatment of choice.