Intimate partner violence (IPV) has been associated with greater vulnerability to HIV infection among women. We examined prevalence and correlates of IPV among female sex workers (FSWs) in Tijuana and Ciudad Juarez, two large Mexico-U.S. border cities where HIV prevalence is rising. Participants were 300 FSWs with a current spouse or a steady partner. Participants' mean age was 33 years, and mean number of years as a sex worker was 6 years. The prevalence of IPV in the past 6 months among participants was 35%. Using multivariate logistic regression, factors independently associated with IPV included having experienced abuse as a child, a partner who had sex with someone else, and lower sexual relationship power. Our findings suggest the need for previous abuse screening and violence prevention services for FSWs in the Mexico-U.S. border region. Careful consideration of relationship dynamics such as infidelity and relationship power is warranted when assessing for IPV risk.