Physicians frequently encounter patients who are at risk for HIV infection, but they often evaluate risk behaviors ineffectively. To describe the barriers to and facilitators of comprehensive HIV risk evaluation in primary care office visits. Qualitative thematic and sequential analysis of videotaped patient–physician discussions about HIV risk. Tapes were reviewed independently by physician and patient and were coded by the research team. Physicians' offices. Convenience sample of 17 family physicians and general internists. Twenty-six consenting patients 18 to 45 years of age who indicated concern about or risks for HIV infection on a 10-item questionnaire administered before the physician visit were included. A thematic coding scheme and a five-level description of the depth of HIV-related discussion. In 73% of the encounters, physicians did not elicit enough information to characterize patients' HIV risk status. The outcome of HIV-related discussions was substantially influenced by the manner in which the physician introduced the topic, handled awkward moments, and dealt with problematic language and the extent to which the physician sought the patient's perspective. Feelings of ineffectiveness and strong emotions interfered with some physicians' ability to assess HIV risk. Physicians easily recognized problematic communication during reviews of their own videotapes. Comprehensive HIV risk discussions included providing a rationale for discussion, effectively negotiating awkward moments, repairing problematic language, persevering with the topic, eliciting the patient's perspective, responding to fears and expectations, and being empathic. Educational programs should use videotape review and should concentrate on physicians' personal reactions to discussing emotionally charged topics.