Methadone treatment reduces HIV risk but the effects of primary care-based buprenorphine/naloxone on HIV risk are unknown. The purpose of the current study was to determine whether primary carebased buprenorphine/naloxone was associated with decreased HIV risk behavior. We conducted a longitudinal analysis of 166 opioid dependent persons (129 men and 37 women) receiving buprenorphine/naloxone treatment in a primary care clinic. We compared baseline, 12 and 24-week overall, drug-related and sex-related HIV risk behaviors using the AIDS/HIV Risk Inventory (ARI). Buprenorphine/naloxone treatment was associated with significant reductions in overall and drugrelated ARI scores from baseline to 12 and 24-weeks. Intravenous drug use in the past 3 months was endorsed by 37%, 12%, and 7%, of patients at baseline, 12 weeks and 24 weeks, respectively; p < 0.001. Sex while you or your partner were "high" was endorsed by 64%, 13%, and 15% of patients at baseline, 12 weeks and 24 weeks, respectively; p<0.001. Inconsistent condom use during sex with a steady partner was high at baseline and did not change over time. We conclude that primary carebased buprenorphine/naloxone treatment is associated with decreased drug-related HIV risk but additional efforts may be needed to address sex-related HIV risk when present. (ClinicalTrials.gov number, NCT00023283).