The Prison Service paid £2.5m in compensation to prisoners in England and Wales last year, figures show.
The biggest single out-of-court payment was for £575,000
Details about the payments, which do not include legal costs, were released under the Freedom of Information Act.
Two jails, Wormwood Scrubs, in London, and Northallerton Young Offenders Institution, in North Yorkshire, were responsible for almost half the total.
Prisoners in 94 jails were compensated over claims of abuse, assault, unlawful detention and medical negligence.
The figures revealed the biggest single out-of-court payment was for £575,000 which was made to a young, male prisoner in Northallerton Young Offenders Institution who had apparently attempted suicide.
Wormwood Scrubs settled one claim for £472,000.
It has not been revealed why these two payments were made, but they were included in a category of injury claims for official misconduct and human rights' breaches.
The figures also showed £750,000 was paid to 197 heroin addicts whose treatment was withdrawn or cut short while they were in prison.
The damages paid to the heroin addicts were approved by a High Court judge last November, following their claims that the practice amounted to an assault and breach of human rights.