This paper explains the most important facts related to imprisonment and its application in Croatian criminal law. First, the concept and types of punishment are explained, as well as the purpose of punishment to make it easier to understand the whole issue. It describes the historical development of imprisonment from the earliest age known to mankind to the present, modern age. The provisions of the Criminal Code relevant to imprisonment are analyzed, in order to obtain a complete picture of its application in Croatian criminal law. Attention is also paid to short-term prison sentences, its disadvantages and alternative sanctions that can replace them. An insight into the problems of the Croatian prison system and its functioning is given. The facts about penitentiaries and prisons, prison staff, the rights of prisoners and the development and work of probation services in the Republic of Croatia are presented. Based on statistical data, the shares of prison sentences imposed in relation to the total number of sentences imposed in the Republic of Croatia in the period from 2017 to 2021 are analyzed.