Injection drug use is a growing but understudied problem in Tijuana, a city situated on the northwestern Mexico-U.S border. The authors studied factors associated with receptive needle sharing in an effort to inform prevention activities. In 2003, street-recruited injection drug users (IDUs) in Tijuana underwent interviews on injection risk behaviors and rapid HIV antibody tests. Logistic regression was used to identify correlates of receptive needle sharing at the last injection episode. Of 402 IDUs, 87.6% were male; the median age was 34. HIV prevalence was 4.01% (95% CI: 2.29-6.51). One third reported receptive needle sharing at last injection. Factors independently associated with receptive needle sharing were years living in Tijuana (Adjusted Odds Ratio [AdjOR]= 0.97 per year, 95% CI: 0.96-0.99), being bisexual/homosexual (AdjOR=2.12; 95% CI: 1.30 - 3.44), unemployed (AdjOR=2.5; 95% CI: 1.52-4.10), never having an HIV test (AOR: 4.02; 95% CI: 2.44-6.60), having friends who placed importance on avoiding HIV (AdjOR: 0.36; 95% CI: 0.19-0.68) and last injecting in a shooting gallery (AdjOR=1.98; 95% CI: 1.21-3.24). These results underscore the need to increase access to voluntary HIV testing and counseling to IDUs and migrants in Tijuana, as well as expand access to sterile syringes in an effort to avert widespread HIV transmission.