Under myelodysplastic syndromes we presume a heterogeneous group of malignant hemopathies with clearly described characteristics of the disease given by a cooperative group of French, American and British authors. Myelodysplastic syndromes most frequently occur at older age. Survival of these patients, after the diagnosis is made, is mostly short because the disease evolves into acute leukemia. Myelodysplastic syndrome is characterized by appearance of refractive anemia, leukemia, thrombocytopenia with signs of expressed dishematopoiesis of the bone marrow. Clear criteria which could define forms with fast or slow course leading to acute leukemia don't exist, so there is a need to group patients into those with good or with bad outcome. The investigation included following parameters important for the outlook of the disease: 1. enlargement of lymph nodes, liver and spleen, 2. biochemical examination of peripheral blood, 3. cytomorphologic changes in the peripheral blood cells and bone marrow. By a follow-up of described parameters a statistically significant influence on survival of the sick concerning the degree of present anemia, absolute number of granulocytes, number of thrombocytes, dishematopoiesis of the peripheral blood and bone marrow, lymphadenomegaly, hepatomegaly and splenomegaly was not found. The percentage of blast in the peripheral blood and bone marrow has a statistically significant influence on patients' short survival.