This study explored local perceptions regarding the potential influence of an HIV vaccine on sexual-risk behaviours in Santo Domingo, Dominican Republic. Qualitative in-depth interviews were carried out with 25 participants, including 15 women and 10 men. Approximately half of the male study participants stated that they would increase their number of sexual partners and/or would not use condoms if they received an HIV vaccine. In contrast, women reported that they would be unlikely to change their own behaviour, but stated that an HIV vaccine would allow them to worry less about the sexual-risk behaviour of their male partners. Our findings suggest the need to utilize existing HIV-prevention programmes to support future HIV vaccine research and distribution efforts and minimize increased risk behaviour. Such efforts should actively assess and address the role of culturally-defined gender norms on behavioural responses to the introduction of HIV vaccines.