Despite significant progress over the last two decades, treatment of HIV infection remains a tremendous challenge. Although antiretroviral therapy has proved quite effective in most HIV-infected patients, increasing recognition of toxicity and the emergence of multidrug resistant HIV strains has fueled the development of alternative therapeutic approaches. Introduction of genes to inhibit HIV replication into CD4+ T lymphocytes or hematopoietic stem cells represents a potentially attractive but still unproven strategy. Despite the availability of a diverse range of molecular strategies that are able to provide potent inhibition of HIV replication in the laboratory, translation of these in vitro successes to in vivo therapies has been difficult. Fundamental challenges facing AIDS gene therapy at the present time includes the need to increase the efficiency of gene transfer in vivo, to confer upon genetically-modified T cells the ability to have a selective growth advantage in vivo, and the development of additional techniques to decrease the probability of emergence of resistant viruses. As one of the leading animal models for AIDS and for hematopoietic stem cell gene therapy, nonhuman primates are ideally suited to help address many of these basic questions. This review will provide a general overview of RNA-based genetic strategies for inhibition of HIV and SIV replication, criteria to be considered in the selection of promising inhibitory strategies for in vivo use, and key questions that can be addressed in the macaque model.