The WHO classification for myelodysplastic syndromes (MDS) has introduced new categories with prognostic relevance. Our aim was to examine the predictive value of the WHO and the FAB classification compared to parameters of peripheral blood, bone marrow and IPSS. Clinical data, peripheral blood counts, bone marrow (BM) cytology and histology and survival were analyzed in consecutive newly diagnosed adult patients with MDS. All cases were diagnosed according to FAB criteria and reclassified by the WHO proposal. Among 150 patients entering the study median age was 58 years (12-90). According to FAB, 90 patients had refractory anemia (RA), 18 sideroblastic anemia, 34 refractory anemia with excess of blasts (RAEB), three RAEB-t and five chronic myelomonocytic leukemia. Using the WHO proposal, one half of the patients with RA changed category. One patient had the 5q-syndrome. There were 25 cases with refractory cytopenias with multilineage dysplasia (RCMD) and 23 WHO "unclassified". These last patients presented few cell atypias, favorable IPSS and a good survival as has been described for refractory cytopenias in pediatric MDS. Hypocellular BM was found in 24% of the patients. Karyotype was available in only 85 cases. In the univariate analysis, both classifications, hemoglobin values, hypercellular bone marrow and IPSS had an influence on survival. Using the bootstrap resampling as stability test for the model created by the multivariate analysis, the WHO classification entered the model in 73%, FAB in 38% and IPSS in only 7%. Therefore, in a setting with a high number of low-risk MDS, the WHO classification is the best predictor of survival of the patients.