Background South Africa is home to the world's largest HIV epidemic. Throughout the world, incarcerated individuals have a higher prevalence of HIV than the general public, and South Africa has one of the highest rates of incarceration in sub-Saharan Africa. In spite of this, little has been published about the burden of HIV and how care is delivered in South African correctional facilities. Objective To estimate the prevalence of people living with HIV and identify initiation and retention in the HIV cascade of care across five correctional facilities. Methods Cross-sectional retrospective analysis of 30,571 adult inmates who participated in a tuberculosis screening and HIV counseling and testing campaign in South African correctional facilities (January 1, 2014-January 31, 2015). Descriptive statistics were used to estimate the proportion and 95% confidence intervals of HIV. Proportions of persons retained and lost at each step in the HIV cascade of care under this intervention were calculated. Poisson regression with robust variance estimates were used, and clustering by facility was accounted for in all analyses. Results Results of the screening campaign found previously undiagnosed HIV among 13.0% of those consenting to screening, with a total estimated HIV prevalence of 17.7% (n = 3,184, 95% CI: 17.2-18.3%) in the sample. When examining the overall cascade of care, 48.3% of those with HIV initiated care, and overall 45.6% of persons who entered care qualified for ART initiated treatment. A Poisson regression accounting for clustering by facility found HIV high risk groups within the population such as women (aRR = 1.72, 95% CI: 1.57, 1.89),