HIV infection is characterized by gradual immune system collapse, hematopoietic dysfunction and the establishment of long term cellular reservoirs. We have found that HIV enters multipotent hematopoietic progenitor cells and establishes active and latent infections¹ . Latent infection of HPC can be reactivated by myeloid differentiation¹ .  In addition, we have found that HIV can infect multipotent progenitors including long-lived hematopoietic stem cells (HSCs) that have the potential to establish viral reservoirs that persist for the life of the infected person.  Specifically, we found that cells targeted by HIV have all the characteristics of hematopoietic stem cells in that they can stably engraft and generate multiple hematopoietic lineages in a xenograft model² . Furthermore, we found that the capacity to use the chemokine receptor CXCR4 for entry determines whether a virus will enter multipotent versus differentiated progenitor cells² . Finally, we demonstrate that HIV genomes can be detected in CD133+ HPCs from a subset of donors with long term viral suppression³ . Because HSCs live for the life span of the infected person and are crucial for hematopoietic health, these data may explain the poor prognosis associated with CXCR4-tropic HIV infection and suggest HSC as long-lived cellular reservoirs of latent HIV.  Strategies that reactive HIV gene expression in HSCs without causing differentiation may help clear these reservoirs⁴ .