Hematologic abnormalities are often seen in patients infected with human immunodeficiency virus (HIV). The effect of HIV infection of bone marrow stroma on support of uninfected CD34 progenitor cells in long-term bone marrow culture (LTBMC) was investigated. Results show that HIV-infected bone marrow stroma was unable to adequately support CD34 progenitor cells in vitro. Zidovudine or didanosine was added to cultures in an attempt to reverse the suppressive effects exerted by HIV and to determine whether such suppression was mediated by transfer of HIV infection to progenitor cells. Didanosine failed to reduce the suppressive effects of HIV, whereas zidovudine compounded the observed suppression. HIV infection of bone marrow stroma, while reducing the production of nonadherent cells, did not increase apoptosis and cell death in such cells. In contrast, zidovudine enhanced apoptosis and cell death in nonadherent cells produced by both HIV-infected and control LTBMC.