Myelodysplastic syndromes (MDS) are hemopathies very common in geriatric practice. They are characterized by qualitative morphological abnormalities of one or more myeloid lineages responsible for an ineffective hematopoiesis, and therefore cytopenias of central origin contrasting with a usually rich bone marrow wealth. The MDS are asymptomatic in half of the cases and their discovery is a result of systematic blood analysis or tests to explore another disease. The evolution is marked by worsening cytopenias, and the risk of acute myeloid leukemia transformation with poor prognosis because frequently chemoresistant. The diagnosis of MDS is pronounced after a clinico-biological confrontation to discuss the differential diagnosis taking into account all clinical and cytological data, results of conventional cytogenetics and evolution after vitamin therapy. Knowledge more depth on MDS refine MDS classification criteria by developing successive classifications (FAB 1982, WHO 2001 and 2008) which aim the identification of MDS groups with clinical, biological and common prognostic. The treatment of MDS is essentially symptomatic. The development of new targeted therapeutic strategies enables high hopes in a context where treatment options are a difficult choice, because the advanced age of most patients. Finally, detailed knowledge of risk factors and prognostic scores are very useful to make the best treatment decisions.