The successful use of small interfering RNAs (siRNAs) for therapeutic purposes requires safe and efficient delivery to specific cells and tissues. In this study, we demonstrate cell type-specific delivery of anti-human immunodeficiency virus (anti-HIV) siRNAs through fusion to an anti-gp120 aptamer. The envelope glycoprotein is expressed on the surface of HIV-1-infected cells, allowing binding and internalization of the aptamer-siRNA chimeric molecules. We demonstrate that the anti-gp120 aptamer-siRNA chimera is specifically taken up by cells expressing HIV-1 gp120, and that the appended siRNA is processed by Dicer; this releases an anti-tat/rev siRNA which, in turn, inhibits HIV replication. We show for the first time a dual functioning aptamer-siRNA chimera in which both the aptamer and the siRNA portions have potent anti-HIV activities. We also show that gp120 expressed on the surface of HIV-infected cells can be used for aptamer-mediated delivery of anti-HIV siRNAs.