Thailand's longstanding HIV epidemic among injection drug users (IDU) has been attributed, in part, to the Thai government's unwillingness to implement evidence-based HIV prevention interventions. This study was undertaken to examine risk factors for syringe borrowing among a community-recruited sample of Thai IDU. The study examined the prevalence of syringe borrowing among 238 IDU participating in the Mit Sampan Community Research Project, Bangkok. Multivariate logistic regression was used to identify independent predictors of syringe borrowing in the past 6 months. A total of 238 IDU participated in this study; 66 (26.2 percent) were female, and the median age was 36.5 years. In total, 72 (30.3 percent) participants reported borrowing a used syringe in the past 6 months, with 47 (65.3 percent) of these individuals reporting multiple borrowing events. In multivariate analyses, syringe borrowing was positively associated with difficulty accessing syringes [adjusted odds ratio (AOR) = 2.46; 95 percent confidence interval (CI): 1.08-5.60] and injecting with other people on a frequent basis (AOR = 3.17; 95 percent CI: 1.73-5.83). Primary reasons offered for experiencing difficulty accessing syringes included being too far from syringe outlets (34.1 percent), pharmacies being closed (13.6 percent) and being refused syringes at pharmacies (9.1 percent). The authors observed an alarmingly high rate of syringe borrowing among a community-recruited sample of Thai IDU. Various lines of evidence indicate that poor access to sterile syringes is driving the high rate of syringe borrowing observed in this study. Immediate action should be taken to increase access to sterile syringes among Thai IDU. Tables and references (Published Abstract)