The topic of this diploma essay is to analyze the current legislation of a special type of criminal sanctions which include the institute of security measures in Croatian criminal law. The Croatian Criminal Code regulates the provisions on security measures in the General Part in Chapter V, in Articles 65 to 76 and elaborates them in the way of listing some of their basic components such as the type and purpose of the measures and explains each of the security measures and certain conditions for their announcement. The focus of this diploma essay will be on the issue of security measure of compulsory psychiatric treatment which will be elaborated thorugh its historical review and relevant legal regulations from the formation of the sovereign Republic of Croatia until today, comparing the security measure of compulsory psychiatric treatment under the Criminal Code of 1997 and the Criminal Code of 2011. which is with all its amendments currently in force. This is followed by description and detailed analysis of the basic elements of which the measure consists, the restrictions to which it's submitted and the appropriate procedures and conditions for imposition and manner of execution that it includes, with emphasis on its encroachment on fundamental human rights and freedoms. The security measure of compulsory psychiatric treatment will also be elaborated through selected case study of the Supreme court of the Republic of Croatia starting from condemnations in which the Court declares and elaborates this security measure on the basis of various mental conditions which require adequate approach. In the last paragraph there will be presented statistics of this security measure by groups of criminal offences in a certain period of time as well as by the category of perpetrators of criminal offence against whom it was imposed regarding the potential danger that such individuals pose to the rest of society.