Introduction: Understanding social and structural barriers that determine antiretroviral therapy (ART) adherence can improve care. Assessment of such factors is limited in Myanmar, a country with high HIV prevalence and increasing number of people living with HIV initiating ART. Methods: Questionnaires were administered to adults with HIV across 4 Myanmar cities to estimate adherence and its potential determinants, including HIV knowledge, social support, barriers to care, enacted and internalized stigma, and engagement in peer-topeer HIV counseling (PC). Associations were determined using logistic mixed-effects modeling. Results: Among 956 participants, the mean age was 39 years, 52% were female, 36% had CD4 <350 cells/mm3, and 50% received pre-ART PC. Good adherence was reported by 74% of participants who had better HIV knowledge than those reporting nonadherence. Among nonadherent, 44% were forgetful and 81% were careless about taking ART. Among all participants, most (53%) were very satisfied with their social support and 79% reported lack of financial resources as barriers to care. Participants most frequently reported being viewed differently by others (30%) and feeling as if they were paying for past karma or sins because of their HIV diagnosis (66%). Enacted stigma (odds ratio 0.86; 95% confidence interval 0.79 to 0.92, P, 0.01) and internalized stigma (odds ratio 0.73; 95% confidence interval: 0.56 to 0.95, P = 0.023) were associated with worse adherence. Conclusions: Increased self-reported ART adherence in Myanmar is associated with less enacted and internalized stigma. These findings suggest the benefit of developing and promoting adherence interventions, which are focused on mitigating HIV-related stigma in the county.