OBJECTIVE: To assess current practices related to prevention with HIV-positive patients in Ryan White-funded primary care settings and the barriers to providing such services. METHOD: Exit surveys about HIV prevention services were conducted with 618 HIV-infected patients at 16 primary HIV care clinics receiving Ryan White CARE Act funding. To place the exit survey findings in context, qualitative in-depth interviews were conducted with 16 clinic administrators, 32 primary care providers, 32 support service providers, and 64 patients. RESULTS: One quarter of patients reported having had a general discussion of "safer sex and ways to prevent transmission to others" during that day's primary care visit. However, only 6% reported discussing specific sexual activities. HIV prevention counseling was less common than counseling for adherence to antiretroviral therapy, emotional issues, and diet and nutrition (P < 0.001). Patients in clinics with established procedures for HIV prevention counseling were significantly more likely to report receiving such services (odds ratio = 2.17). Qualitative interviews identified barriers to providing prevention services as lack of time, training, funding for staffing, and providers' understanding of their roles and responsibility. CONCLUSIONS: HIV prevention counseling is not routine in most clinics, and the low frequency of such services represents missed opportunities for HIV prevention.