Criminality in all its forms jeopardizes the economic, social and cultural development and progress of society and the state and the quality of life of its citizens. A prison sentence for many reasons, primarily social and economic, has long been a key tool in combating criminality. The prison system, with the police and the judiciary, is the last in a series that protects the victim and the society as a whole from the perpetrators of criminal offenses and prevents them from further perpetrating criminal offenses, hence the execution of prison sentences of particular interest to the Republic of Croatia. Modern prisons should reflect the needs of time and reflect the society as a whole. The key to good and secure prison facilities lies in the quality of the relationship between two groups of people, namely prisoners and officials, i.e. prison staff responsible for executing prison sentences. Prison management should take place within high ethical standards. The relationship between prisoners and staff is the key to good prison management. Within the prison system, the most important interest groups are citizens, i.e. society as a whole, prison staff and prisoners themselves. Also, persons in charge of prisons and prison systems should have a wider picture of the whole system and, in addition to technical processes and procedures, to ensure a fair, just and humane treatment within a criminal institution, as well as to find new ways of improving and optimizing the system itself.