Aimsâ To identify factors associated with receptive syringe sharing among injection drug users (IDUs) and elucidate the association between syringe possession arrests and syringe sharing.Designâ Crossâsectional study.Settingâ Mexican border cities of Tijuana, Baja California and Ciudad Juarez, Chihuahua.Participantsâ IDUs in Tijuana (nâ=â222) and Ciudad Juarez (nâ=â206) were recruited using respondentâdriven sampling (RDS). IDUs were â„â18âyears and had injected illicit drugs in the past month.Measurementsâ An interviewerâadministered survey was used to collect quantitative data on socioâdemographic, behavioral and contextual characteristics, including selfâreported syringe sharing and arrests for syringe possession. Associations with receptive syringe sharing were investigated using logistic regression with RDS adjustment.Findingsâ Overall, 48% of participants reported ever being arrested for carrying an unused/sterile syringe, even though syringe purchase and possession is legal in Mexico. Arrest for possessing unused/sterile syringes was associated independently with receptive syringe sharing [adjusted odds ratio (AOR)â=â2.05; 95% confidence interval (CI): 1.26, 3.35], as was injecting in a shooting gallery (AORâ=â3.60; 95% CI: 2.21, 5.87), injecting in the street (AORâ=â2.05; 95% CI: 1.18, 3.54) and injecting methamphetamine (AORâ=â2.77; 95% CI: 1.41, 5.47) or cocaine (AORâ=â1.96; 95% CI: 1.15, 3.36). More than half of participants (57%) had been arrested for possessing a used syringe; in a second model, arrest for used syringe possession was also associated independently with receptive sharing (AORâ=â2.87; 95% CI: 1.76, 4.69).Conclusionsâ We documented high levels of syringeârelated arrests in two MexicanâUS border cities and an independent association between these arrests and risky injection practices. Public health collaborations with law enforcement to modify the risk environment in which drug use occurs are essential to facilitate safer injection practices.