Since AIDS was first recognized as a unique clinical entity, a massive amount of effort has been devoted to the understanding and control of HIV infection. Several early reports indicated that HIV could infect cells of macrophage lineage, and, more recendy, the interactions between HIV and dendritic cells have become clearer. However, these cells have a special biology which has not always been taken into account by HIV researchers, although the virus itself has evolved special variants with the capacity to infect macrophages. Accordingly, the Second International Workshop on HIV and Cells of Macrophage Lineage was held in Sydney, Australia on December 6 and 7, 1993, in conjunction with the joint meeting of the Australasian Society for Immunology and the Society for Leukocyte Biology. The Organizers were Suzanne Crowe, Tony Cunningham, Richard Kornbluth, Monte Meltzer, and John Mills. Largely through the generosity of the Australian government, the Australian National Centre in HIV Virology Research, and the Society for Leukocyte Biology, this workshop brought together many of the investigators actively working in this field (although neither funds nor time allowed the complete meeting of all the investigators interested in this field). This special issue of the Journal of Leukocyte Biology originated with the ideas presented at this Workshop and provides a partial view of where this field has arrived. In addition, five papers on HIV-induced neuropathology have been included in a minisymposium put together independently of the Workshop by Howard Gendelman.