OBJECTIVE: To assess baseline rates of and changes in HIV drug and sexual risk behavior as a function of gender and treatment in opioid-dependent youth. METHODS: One hundred fifty participants were randomly assigned to extended buprenorphine/naloxone therapy (BUP) for 12 weeks or detoxification for 2 weeks; all received drug counseling for 12 weeks. HIV risk was assessed at baseline and 4-week, 8-week, and 12-week follow-ups. Behavioral change was examined using generalized estimating equations. RESULTS: Baseline rates of past-month HIV risk for females/males were 51%/45% for injection drug use (IDU) (ns), 77%/35% for injection risk (P < 0.001), 82%/74% for sexual activity (ns), 14%/24% for multiple partners (ns), and 68%/65% for unprotected intercourse (ns). IDU decreased over time (P < 0.001), with greater decreases in BUP versus detoxification (P < 0.001) and females versus males in BUP (P < 0.05). Injection risk did not change for persistent injectors. Sexual activity decreased in both genders and conditions (P < 0.01), but sexual risk did not. CONCLUSIONS: Overall, IDU and sexual activity decreased markedly, particularly in BUP patients and females, but injection and sexual risk behaviors persisted. Although extended BUP seems to have favorable effects on HIV risk behavior in opioid-dependent youth, risk reduction counseling may be necessary to extend its benefits.