The current transmission of AIDS in Vietnam is mostly linked to drug injection, but there is potential of a sexual epidemic. HIV education programs focus on the personal responsibility model of risk, yet failing to address adequately other aspects of HIV risks in social contexts. This paper examines the association between AIDS risks (unsafe drug use and unsafe sex) and gender relations among injecting drug users (IDUs). The study is based on ethnographic fieldwork conducted in 2002 in Northern Vietnam. Three patterns of heterosexual intimate relationships are analysed: 1- IDU-IDU relationship; 2- IDU-Smoker relationship; and 3- IDU-Non-user relationship. Data shows that intimate relationships play an important role in managing AIDS risks among IDUs. Trust and love can be seen as solutions to dangers and uncertainties. In some cases, women could exert control over the use of condom in contrast with the implied subordination of women. There is significant variability in the perceived effects of heroin on sexual experience. Care and responsibility confer different meanings in the drug scene. It is argued that HIV prevention and harm reduction programs must pay due attention to the specific context of IDUs’ lives. Some implications of these findings are discussed and relevant recommendations are proposed.