A decade of clinical trial experience with the preventive use of ALVAC-HIV (Aventis Pasteur) has revealed important information on the safety and immunogenicity of HIV vaccines in general. The ability to induce mucosal immune responses and the feasibility of assessing those responses with a systemically delivered HIV vaccine was recently shown with ALVAC-HIV. A critical advance for the HIV vaccine field was the reported direct relationship between cellular immune responses to ALVAC-HIV vaccine in human leukocyte antigen (HLA) B27 and HLA B57 carriers, alleles linked with a favorable HIV prognosis in the setting of natural infection. Other advances include the use of ALVAC-HIV as a heterologous viral boost to enhance cellular responses to an adenovirus-HIV vaccine. All of these observations have important implications for the future of HIV vaccines and need to be considered in the design of the next generation of products.