In 2016 the WHO will publish revised new MDS typing, so why are these revisions being made and what are the benefits? The principles of MDS staging nomenclature are morbid hematopoiesis and primitive cell and monocyte counts, and all types of hematocrit, although not the main principle, still have an important place in the nomenclature of each MDS staging, as well as in the prognostic scoring. The criteria for determining primitive cells remain unchanged. The quantitative criteria for morbid hematopoiesis are still 10%, with more detailed description and qualification regarding specific morbid hematopoiesis. The proportion of primitive cells has an important role in prognosis and staging, so even if the proportion of primitive cells is <5%, the specific proportion should be written, especially if it is below 2%. This is because in the prognostic score, those with a <2% primitive cell count have a better prognosis. This criterion remains unchanged for the diagnosis of acute myeloid leukemia with a primitive cell ratio of 20%. There are new changes regarding refractory anemia with unilineage diseased hematopoiesis (MDS-RCUD). RA and RARS subtypes are mono-erythropoietic, but mono-erythropoietic may also occur in granulocytic, refractory neutropenia (RN), and megakaryocytic, refractory thrombocytopenia (RT), although these cases are less common than mono-erythropoietic. Patients with refractory neutropenia and thrombocytopenia have been seen clinically with disease progression to higher risk MDS and even leukemia. Most patients with MDS with unilineage morbid hematopoiesis present with first-lineage hematocrit, but refractory anemia with unilineage morbid hematopoiesis (RCUD) and RARS are seen with second-lineage hematocrit. In subsequent applications, it was found that the series of pathological hematopoiesis and the series of hematocrit were sometimes inconsistent, as in the case of erythropoietic pathological hematopoiesis, but the clinical presentation was neutropenic. Therefore, this typing suggested that RCUD no longer be divided into three subtypes, and that the previous RCUD-RA, RCUD-RN, and RCUD-RT, be unified into RCUD and not be subdivided that way. And given the independent good significance of cyclic iron granulocytes in prognosis and the fit with molecular biological indicators (SF3B1 mutation), cyclic iron granulocytes, again, are singled out. The former refractory anemia with RARS was replaced by MDS with RARS with monophytic hematopoiesis; refractory hematopenia with multilineage hematopoiesis (RCMD) with RARS was divided into: MDS with RARS and multilineage hematopoiesis, and MDS with multilineage hematopoiesis. For the diagnosis of MDS-U, a peripheral blood primitive cell count of 1% is required to be measured at a minimum of two different times, thus classifying RCUD or RCMD, when combined with a primitive cell count of 1%, as MDS-U. The morphology is consistent with RCUD (i.e., monophytic hematopoiesis only), but if a complete hematocrit is achieved - ANC < 1.8x109/L, Hb<10g0/L, Plt<100x109/L, the diagnosis is MDS-U. The diagnosis is MDS-U when the quantification of pathological hematopoiesis is less than 10% and the peripheral blood primitive cells are less than 1% and the bone marrow primitive cells are less than 5%, but there are MDS-specific associated chromosomal abnormalities. 1.Secondary lineage hematopoiesis is occasionally seen, and whole blood cytopenia should be diagnosed as MDS-U. 2. RAEB-1 is diagnosed if the primitive cells are <5% in bone marrow and 2-4% in peripheral blood. e.g. 1% peripheral blood primitive cells in patients with RCDD and RCMD should be diagnosed as MDS-U. 3. RAEB-2 should be diagnosed with Auer microsomes and primitive cells <5% in peripheral blood and <10% in bone marrow.