The paper deals with and analyzes the institution of immunity in criminal proceedings, which represents an exemption from duty or punishment, that is, a privilege or mercy to a certain person. Immunity in criminal proceedings is determined both by the regulations of internal and international law, that is, by formal legal sources. Pursuant to the constitutional provisions of internal law, members of the Croatian Parliament, the President of the Republic of Croatia, judges of the Constitutional Court of the Republic of Croatia, judges, lawyers, state attorneys and crown witnesses have immunity from criminal proceedings. According to international law, immunity from criminal proceedings of persons who enjoy the right of extraterritoriality - diplomatic immunity, persons who enjoy consular immunity, persons who have the status of international officials , persons who enjoy salvus conductus, an institution of medieval law that guaranteed the perpetrator that the court would not imprison him during the trial if he responded to the summons and appeared at the trial, today serves witnesses and experts as a guarantee that criminal proceedings will not be initiated against them in the requesting state their help. In addition to the above, it is important to emphasize immunity according to the position of the European Court of Human Rights, which states in Art. 6 of the Convention on the importance of the right to a fair trial.