Myelodysplasia, characterized by varied reductions of peripheral blood elements with normal or hypercellular bone marrow, is relatively frequent among older patients and may evolve to acute leukemia. We reviewed findings in 35 patients whom, according to the FAB classification were distributed as follows: simple refractory anemia (RA) 34%, sideroblastic refractory anemia (SRA) 14%, refractory anemia with excess blast forms (RAEB) 31%, chromic myelomonocytic leukemia (CMML) 12% and refractory anemia with excess blast forms in transformation (RAEBT) 9%. Cytogenetic studies performed in 16 patients were abnormal in 5 (31%), all among patients with poor prognosis forms of the disorder. All patients had anemia; thrombopenia and neutropenia were more frequent in subtypes RAEB, CMML and RAEBT). Mean survival rate was 30 months, significantly greater in RA and SRA compared to the other groups. Infections and development of acute leukemia were the causes of death.