Injecting drug use plays a critical role in the transmission of HIV in Vietnam. This paper provides a comprehensive review of studies on risks of HIV infection among injecting drug users (IDUs) in Vietnam. Current research evidence shows that the age at which drug initiation starts is becoming younger and the transition time between non-injecting to injecting drug use becoming shorter. The practice of needle sharing and unprotected sex was quite common among the IDUs. Although most of the IDUs generally had good knowledge of HIV transmission routes, most IDUs were not aware of their infection status. Data from a national surveillance programme shows that a third of the IDUs were HIV positive. Amongst all HIV positive cases, almost two-thirds had a history of intravenous drug use. A number of studies have identified a range of risk factors and barriers to minimize the risk of HIV infection in IDUs. This paper discusses these issues and makes recommendations for changes to HIV/AIDS policies, programme interventions as well as future research on the topic.