Arguably one of the most marginalized populations in our society, prisoners bear a disproportionate burden of infectious diseases, particularly HIV. In addition, groups known to be at an inordinately higher risk of HIV, including minorities, the addicted, the mentally ill and the impoverished are overrepresented among incarcerated populations. This concentration of HIV among groups that have been historically difficult to reach, with limited intersections with healthcare, provides an opportunity for testing, diagnosis, treatment, linkage to care and prevention. Providing HIV care within correctional facilities poses unique challenges. Barriers to confidentiality, access to medication and prior records, and lack of comprehensive discharge planning can serve as obstacles to providing optimal care. This article discusses the public health implications and importance of providing HIV care to prisoners, and also discusses the practicalities of working within an environment that poses particular barriers to care.