This article characterises the systems of executing the penalty of imprisonment as stipulated in Article 81 of the Executive Penal Code of 1997. The article examines the differences in the systems of executing the penalty of imprisonment in relation to the categories of convicts to whom individual systems are addressed and in relation to the principles used to select correctional measures. The diversity of the systems of executing the penalty of imprisonment corresponds to the principle of individualisation in dealing with convicts, which meets the needs related to the execution of the penalty of imprisonment.