South America is a heterogeneous continent, with diverse prison realities. Its prison population is estimated at 600,000 inmates, of whom 10,000 are declared insane. Physical and mental health care supplied to the inmates is precarious and preventive programs in progress are rare. The authors' comment on the Roman Law tradition and describe the situation in Brazil and Argentina, from the point of view of their legal backgrounds. They also consider the kind of mental health resources found and the types of treatment offered, mainly in Forensic Psychiatric Hospitals. Their conclusion emphasizes the need to improve the conditions of penitentiaries in South America, which, because of their deficiencies, often violate the human rights of prisoners.