Intravaginal practices such as "dry sex" and douching have been suggested as a risk factor that may increase women's susceptibility to HIV infection. These behaviours appear common in different populations across sub-Saharan Africa, where practices include the use of antiseptic preparations, traditional medicines, or the insertion of fingers or cloths into the vagina. We systematically review the evidence for the association between women's intravaginal practices and HIV infection. Although a number of cross-sectional studies have shown that prevalent HIV infection is more common among women reporting intravaginal practices, the temporal nature of this association is unclear. Current evidence suggests that bacterial vaginosis, which is a likely risk factor for HIV infection, may be a mediator of the association between intravaginal practices and HIV. Although biologically plausible mechanisms exist, there is currently little epidemiological evidence suggesting that intravaginal practices increase women's susceptibility to HIV infection. Further research into factors that increase women's susceptibility to HIV will help to inform the design of vaginal microbicides and other HIV prevention interventions.