It has been demonstrated that some myeloid blasts express renin, but normal bone marrow (BM) does not display this expression. The aim of the present work was to analyze the renin expression in different hematological malignancies and different myeloid cell lines. We investigated the expression of renin by RT-PCR in BM from patients with hematological malignancies (106 patients), in nine normal BM from healthy donors and in leukemic cell lines (K562, KU812, MEG-01, U-937 and HL60), as well in K562 cell line subjected to differentiation treatments. We have observed renin expression in cells from acute myeloid leukemia (AML), chronic myelogenous leukemia (CML) and acute lymphoblastic leukemia (ALL) cases. The highest frequency was observed in AML-non acute promyelocytic leukemia(APL) cases (47.2% of the cases). The disappearance of this expression was associated with the status of complete remission of AML. Renin is expressed in some myeloid human leukemia cell lines such as K562, KU812 and MEG-01. However, when K562 cells were treated with inducers of growth inhibition and/or differentiation, the expression did not disappear, indicating that renin expression is associated with a blastic phenotype rather than with cell proliferation. The obtained findings suggest that the renin expression could have a role on the disease development and could be used as an aberrant marker of leukemia.