Detainees are one of the most vulnerable populations to human immunodeficiency virus (HIV). This is mostly caused by the lack of knowledge on the topic among the inmates; the lack of prophylaxis; the high percentage of risky behaviors in jail, such as sexual abuse, unprotected sexual intercourses, and injective drug use; and the generally low perception of the risk of transmission. It has also been observed that the problem does not cease to exist at the moment of release, but it also may be aggravated by the weak support system or the total absence of programs for people living with HIV/AIDS (PLWHA) to avoid discontinuation of antiretroviral drugs. Difficulty in providing housing and jobs and, therefore, a form of stability for ex-detainees, also contributes to none adherence to antiretroviral therapy. Among the detainees, there are also categories of people more susceptible to discrimination and violence and, therefore, to risky behaviors, such as black people, Hispanics, transgender people, and men who have sex with men (MSM). We reviewed the literature in order to provide a more complete picture on the situation of PLWHA in jail and to also analyze the difficulties of ex-detainees in adhering to HIV therapy.