Focus group discussions were conducted to assess factors that might impact participation of subgroups in Chennai for future HIV vaccine trials. The participants were 112 men and women representing the following: (1) transport workers; (2) clients who attended a sexually transmitted disease clinic; (3) injection drug users; (4) men having sex with men; (5) women in sex work; and (6) monogamous married women. Participants expressed an intense interest in future HIV vaccine trials. Willingness to participate in future trials included altruism and the desire to have a protective vaccine for the future. Assurances regarding stigma and confidentiality, and compensation for families in the event of a poor outcome with a future HIV vaccine trial were reported. Concerns also centered on the impact of seroconverting, and a possible increase in risk behaviors. The need for education and counseling about the dangers of engaging in risky behavior during and after participating in a future HIV vaccine trial is discussed.