Transgenic technology has been very successful at providing insights into possible processes involved in HIV-induced pathogenesis. The availability of these small animal models for the study of HIV-related syndromes including KS, epidermal proliferative lesions, HIV-associated nephropathy, AIDS-related growth failure and cachexia may well facilitate the development of novel therapies for these complications. Other phenotypes created in mice, such as cataracts and hepatic cancer [59], may not have human analogies but may still provide insight into pathogenesis. Thus, transgenic models have already provided resources to study many manifestations of AIDS and others are likely to be developed. The optimal strategy for designing future transgenic animals, however, is less clear. No transgenic mouse model has been generated to date that will provide an avenue for vaccine development. This advance awaits the further discovery of the host factors that facilitate the virus replicative cycle in humans and a better understanding of these pathways in the mouse. For the development of molecular-based therapy, however, the currently available models may well be adequate to test molecular inhibitors of transcription [7,60,61] and post-transcriptional processing of viral mRNA [62]. Whether single or multigenic constructs under the control of the LTR are better or worse for this purpose is a debatable issue. Transgenic technology may yet make an additional contribution to the development of molecular therapy for AIDS. The best method of demonstrating that a gene therapeutic strategy is safe to administer to patients has not been determined. By introducing potentially therapeutic constructs into mice as transgenes, their safety can be assessed in many different cell types in vivo, analogous to toxicological testing in rodents for systemically administered drugs. Thus, transgenic technology has already provided insights into the pathogenesis of HIV-1. While it has not yet proven its utility for vaccine development, transgenic technology holds the promise of being an active participant in the development of both safe and effective gene therapy approaches for the treatment of AIDS.