Abstract Aging of hematopoietic stem cells (HSCs) is linked to various blood disorders. But how HSC aging and sex co-influence leukemogenesis is poorly understood. By examining HSC aging in young, aging (75% lifespan) and longevity (110% lifespan) mice in males vs females, we have discovered that aging males have a significantly higher HSC frequency than females, and that male HSC aging is characterized by an expansion of Lin-CD150+SP HSCs and a decrease of Lin-CD150-SP HSCs, whereas females show opposite HSC changes towards aging and longevity. In line with HSC changes, aging males exhibit an increase of white blood cell counts that is primarily driven by increased myeloid cells, whereas aging females shows a decrease of white blood cell counts that is primarily driven by reduced lymphoid cells. To understand leukemogenic potential of aging HSCs in the true setting of organismal aging, we generated the first aging mouse model of chronic myeloid leukemia (CML) induced by BCR-ABL1 (Oncogene, 2021, 40: 3152-3163). We found that aging male HSCs are significantly more susceptible to BCR-ABL1 transformation and CML induction in aging male mice than aging female HSCs for CML induction in aging female mice. However, in the absence of oncogenic translocation genes, longevity female but not male mice rapidly develop B/myeloid mixed phenotype acute leukemia, a disease of HSC origin, in primary bone marrow transplantation recipients. Leukemias in our aging mouse models phenocopy those of humans in that the incidence of myeloid leukemia is higher in aging men than in women overall, but longevity women have a higher incidence of myeloid leukemia. Using single cell RNA sequencing analysis of HSCs, we found distinct cell clustering patterns and signaling pathways of aging HSCs between male and female mice. The top pathways seen in male HSC aging involve TGFβ and TNFα signaling that have been linked to poor drug response and persistence of human CML stem cells, while those for female HSC aging involve IFNα/γ signaling pathways that have been associated with good drug response of human CML stem cells. Together, our results demonstrate sex-dependent HSC aging and leukemogenic potential and that molecular changes in aging HSCs can inform drug response of leukemia stem cells. Our findings provide novel insight into the etiology of leukemia in males vs females and suggest potential benefit to use sex-based prevention and therapeutic strategies for leukemia in men vs women. Citation Format: WenYong Chen. Sex-dependent hematopoietic stem cell aging and leukemogenic potential [abstract]. In: Proceedings of the AACR Special Conference: Aging and Cancer; 2022 Nov 17-20; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_1):Abstract nr A013.