BACKGROUND: The HIV epidemic is intertwined with substance use and incarceration in Russia. The relationships between incarceration history, HIV treatment history, and stigma experiences among people with HIV (PWH) who inject drugs in Russia have not been well described. METHODS: We conducted a cross-sectional study of a cohort of PWH with opioid use disorder who inject drugs (n=201) recruited at a narcology (substance use treatment) hospital in St. Petersburg, Russia from September 2018 to December 2020. The primary analysis evaluated the association between self-reported prior incarceration and prior antiretroviral therapy (ART) initiation using multivariable logistic regression to adjust for demographic, social, and clinical covariates. We used multivariable linear regression models to analyze associations between prior incarceration and two secondary outcomes: HIV stigma score (11-item abbreviated Berger scale) and substance use stigma score (21-item combination of Substance Abuse Self-Stigma Scale and Stigma-related Rejection Scale). RESULTS: Mean age was 37 (SD 5) years; 58.7% were male. Participants had been living with HIV for a mean of 13 (SD 6) years. Over two thirds (69.2%) of participants reported prior incarceration. One third (35.3%) of participants reported prior ART initiation. Prior incarceration was not significantly associated with prior ART initiation (AOR 1.76; 95% CI: 0.81, 3.83). Prior incarceration was associated with a lower HIV stigma score (adjusted mean difference in z-score: -0.50; 95%CI: -0.81, -0.19) but was not significantly associated with substance use stigma score (adjusted mean difference in z-score: -0.10; 95%CI: -0.42, 0.21). CONCLUSION: Prior incarceration was common, and rates of prior ART initiation were low even though most participants had been living with HIV for at least a decade. We did not find an association between prior incarceration and prior ART initiation, which suggests a need to explore whether opportunities to initiate ART during or after incarceration are missed. CLINICAL TRIAL NUMBER: NCT03290391.