This study examined the effectiveness of a combined counseling and case management behavioral intervention, using motivational interviewing strategies, in engaging Hispanic injection drug users in treatment and reducing drug use and injection-related HIV risk behaviors. Follow up data are presented on 440 (79.0%) of 557 randomized participants, 6 months after the initial interview. Subjects in the experimental arm were significantly less likely to continue drug injection independent of entering drug treatment, and were also more likely to enter drug treatment. Subjects in both arms who entered drug treatment were less likely to continue drug injection. Among subjects who continued drug injection, those in the experimental arm were significantly less likely to share needles. Confirming the outcomes of this study in other Hispanic sites and populations could be a critical step towards reducing factors that contribute to the self-sustaining HIV/AIDS epidemic in Puerto Rico and communities in the U.S. mainland.