Multiparametric flow cytometry is a useful co-criterion for diagnostic confirmation of MDS in patients with peripheral cytopenias and a normal karyotype. We examined the impact on patients' survival of several phenotypic aberrancies detected by a small 4-color panel of monoclonal antibodies (MoAbs). Diagnosis of the patients (54) was made by WHO criteria using peripheral blood counts, bone marrow (BM) morphology and karyotype. Flow cytometry was performed at diagnosis, and features obtained were compared to normal BM (24). We could detect 16 alterations: 4 in granulocytic precursors, 4 in monocytes, 6 in CD34+ cells, beside changes in plasmacytoid dendritic cells and basophil precursors. The total number of changes in RAEB was higher (median 8) than in cases with of abnormalities) were independent risk factors for a shorter survival. Our panel was sufficient to confirm the diagnosis of MDS and permitted to detect independent prognostic features.