In the recent issue, we have reported two cases of myelodyslastic syndrome (MDS) with a novel unbalanced whole-arm ranslocation der(5;19)(p10;q10) . This translocation was ccompanied by an additional normal chromosome 19 and escribed as der(5;19)(p10;q10),+19,which resulted inmonosomy q and trisomy 19q. Furthermore, both patients presented sevral common clinical and hematological findings. That is, MDS ubtypes were advanced stage, refractory anemia with excess lasts (RAEB)-1 and RAEB-2. Peripheral blood showed leukoeryhroblastosis, and marked anemia and thrombocytopenia without eutropenia. Bonemarrow demonstrated trilineage dysplasia with rominent dyserythropoiesis. Myeloblasts expressed CD7 as well s myeloid markers. Besides der(5;19),+19, additional cytogenetic berrations involving chromosomes 6, 17 and18were found. These ndings suggest that the der(5;19) might constitute a distinct clincal entity in high-risk MDS. In this letter, we report two new cases f MDS and acute myeloid leukemia (AML) arising from MDS with er(5;19).