People living with HIV/AIDS (PHAs) are increasingly recognized as experts in HIV and their own health. We developed a simulated clinical encounter (SCE) in which medical students provided HIV pre- and post-test counselling and point-of-care HIV testing for PHAs as patient instructors (PHA-PIs) under clinical preceptor supervision. The study assessed the acceptability of this teaching tool with a focus on assessing impact on HIV-related stigma among medical students. University of Toronto pre-clerkship medical students participated in a series of SCEs facilitated by 16 PHA-PIs and 22 clinical preceptors. Pre- and post-SCE students completed the validated Health Care Provider HIV/AIDS Stigma Scale (HPASS). HPASS measures overall stigma, as well as three domains within HIV stigma: stereotyping, discrimination, and prejudice. Higher scores represented higher levels of stigma. An additional questionnaire measured comfort in providing HIV-related care. Mean scores and results of paired t-tests are presented. Post-SCE, students (n  = 62) demonstrated decreased overall stigma (68.74 vs. 61.81, p  < .001) as well as decreased stigma within each domain. Post-SCE, students (n  = 67) reported increased comfort in providing HIV-related care (10.24 vs. 18.06, p  < .001). Involving PHA-PIs reduced HIV-related stigma among medical students and increased comfort in providing HIV-related care.