This paper examines the link between heterosexual marriage and women's vulnerability to HIV in Indonesia. In this country, gender relations are currently dominated by traditional beliefs and practices and by religious morality. Data for the current study were collected by means of documentary analysis and archival research as well as by means of expert informant interviews. Findings suggest that traditional practices such as polygamy, early marriage and contract marriage (mut'a) play an important role in enhancing women's likelihood of acquiring HIV within the Indonesian context.