Successful conduct of HIV vaccine trials in a population of great cultural diversity like India could be a challenge. Concerns, knowledge gaps and willingness to participate in future HIV vaccine trials were studied among 349 patients attending three sexually transmitted infections clinics and one reproductive tract infections clinic. Overall willingness to volunteer for HIV vaccine trials was 48%. Women and men at risk of HIV infection were willing to participate in the HIV vaccine trials. Factors associated with increased willingness to participate in these trials were awareness of current HIV vaccine efforts, realization of importance of vaccine for self, concern about adverse events and altruism.