In French Guiana, 4.5-5.0% of HIV-infected persons experienced an incarceration between 2007 and 2013. A cross-sectional survey was performed to describe the epidemiology and treatment outcomes of a population of HIV-infected inmates in French Guiana. The study population was patients released between 1/2007 and 12/2013, after >30 days of incarceration (n = 147). A secondary objective aimed to identify its main specificities, relative to both the general inmate population and the nonincarcerated HIV population. The socioeconomic situation of HIV-infected inmates was particularly precarious, relative to other detainees: 58.1% had never attended school (versus 5.5%, p < 0.01), 31.0% were homeless (versus 8.5%, p < 0.01), 63.9% were repeat offenders (versus 46.6%, p < 0.01), 33.3% were crack cocaine users (versus 9.8-12%, p < 0.01). The frequency of hypertension and chronic B hepatitis was also higher. Only 50.3% of inmates were on antiretroviral therapy (ART) versus 92.6% in the hospital HIV population (p < 0.001). Among untreated patients, 15.1% refused ART. Among those treated, 81.3% were virologically suppressed. Although comparisons were biased, HIV-positive inmates had more psychosocial vulnerabilities than the general inmate population. Despite ART availability and excellent treatment outcomes, undertreatment was a fact not completely explained by patient refusal. HIV-infected inmates should benefit from increased attention by health care and social workers.