Several groups have published flow cytometry scores useful for the diagnosis or prognosis of myelodysplastic syndromes (MDS), mainly based on the detection of immunophenotypic abnormalities in the maturation of granulocytic/monocytic and lymphoid lineages. As anemia is the most frequent symptom of early MDS, the aim of this study was to identify markers of dyserythropoiesis relevant for the diagnosis of MDS analyzed by selecting erythroblasts in a whole no-lysis bone marrow strategy by using a nuclear dye. This prospective study included 163 patients, including 126 with cytopenias leading to MDS suspicion and 46 controls without MDS. In a learning cohort of 53 unequivocal MDS with specific markers, there was a significant difference between the coefficients of variation of mean fluorescence intensities of CD71 and CD36 in MDS patients compared with controls. These two parameters and the hemoglobin level were used to build a RED-score strongly suggestive of MDS if ≥ 3. Using the RED-score in the whole cohort, 80% of MDS or non-MDS patients were correctly classified. When combined with the flow score described by Ogata et al., this strategy allowed to reach a very high sensitivity of 88% of patients correctly classified.