Although dramatically heightened rates of violence have been observed among injection drug users (IDU), little is known about the gender differences associated with violence among this population. Employing a risk environment framework, we performed an analysis of the factors associated with experiencing violence among participants enrolled in a prospective cohort study of IDU during the years 1996-2005 using generalized estimating equations (GEE). Among 1114 individuals, 291 (66%) of females and 470 (70%) of males reported experiencing violence during the study period. In multivariate analyses, mental illness, frequent alcohol use, frequent crack use, homelessness, Downtown Eastside residency, and requiring help injecting were positively associated with experiencing violence for both sexes (all p<0.05). For females, binge drug use (AOR=1.30) and drug dealing (AOR=1.42) were positively associated with violence, while younger age (AOR=1.02), frequent heroin injection (AOR=1.24), and incarceration (AOR=1.50) were significant for males. Women were more likely to be attacked by acquaintances, partners, and sex trade clients, while men were more likely to experience violence from strangers and the police. These findings indicate that susceptibility to violence among IDU is structured by environmental factors such as homelessness and drug-related factors such as frequent alcohol use and involvement in drug economies. Furthermore, important gender differences with respect to the predictors and characteristics of violent attacks do exist. These findings indicate an urgent need for the development of comprehensive programs and structural interventions that take a gender-focused approach to violence among IDU.