This paper is about special investigative measures, their position in the criminal procedure, as well as their limiting influence of basic human rights that are guaranteed by the Constitution and Convention. In the paper there are all material and formal assumptions that are required for special evidentiary actions. Further on the paper explains the way of conducting the special investigative measures and it analyzes special investigative measures in the context of the law on criminal procedure Also there are explanations of verdicts against Republic of Croatia in front of the European court of human rights. In the following part of the paper there are explanations of some of the special evidentiary actions, for example the use of the covert investigators and confidants , as well as the way they are conducted and possible problems that can occur. In the conclusion there is a critical review of the legal regulations in Croatia.