Refractory anemia with excess blasts in transformation (RAEB-T) is characterized by dysplastic features of the myeloid and usually erythroid progenitor cells in the bone marrow and an increased number of myeloblasts in the peripheral blood. The peripheral blood blast count ranges from 20% to 30%. RAEB-T used to be a subcategory of myelodysplastic syndromes in the past. Recently, the term has been eliminated from the WHO based classification of myelodysplastic syndromes. The reason is that the percentage of peripheral blood blasts required for the diagnosis of acute myeloid leukemia has been reduced to 20%. The elimination of the RAEB-T term by the WHO experts has created confusion and ongoing arguments. Currently, according to WHO classification, the vast majority of RAEB-T cases are best classified as acute leukemias (acute leukemias with multilineage dysplasia following myelodysplastic syndrome). A minority of cases are part of RAEB-2.