This qualitative study identifies the types of professional expertise that physicians are seen to possess in clinical encounters from the perspective of people living with HIV/AIDS (PLWHA). Respondents looked to their physicians for expert knowledge in 3 key areas: medical/clinical; legal/statutory; and ethical/moral. Physicians were seen to be authorities in each of these areas and their judgments, though not always agreed with, were taken seriously and influenced the health care decisions made by PLWHA. The authority that comes with professional expertise in each of the areas identified was experienced both positively and negatively by PLWHA. Understanding the expectations of patients in the medical encounter can assist physicians in providing optimal care in the management of HIV/AIDS.