Since new therapeutic strategies are emerging in myelodysplastic syndromes (MDS), a refined diagnostic procedure of the several subgroups of MDS is of increased importance. Multidimensional flow cytometry may add significantly to a more detailed analysis of the hematopoietic lineages with respect to qualification and quantification of bone marrow cells and is described in detail. Clearly defined aberrancies on myeloid immature and maturing cells are now identified with possible impact on diagnosis, classification and prognostication in the near feature.