The aim of this paper entitled "Development of security companies in the Republic of Croatia" was to determine the development of security companies in the Republic of Croatia. Thus, the paper investigated the legal basis and basic indicators of the activities of security companies in the Republic of Croatia. An effort was made to investigate security companies from the beginning of their creation. Various scientific research methods were used to achieve the goal. The following can be mentioned: analysis, synthesis, and comparison of information and data from publicly available sources. Other scientific research methods applicable to the planned research were also used, such as elements of statistics, etc. Also, the entire issue of this work was viewed from a forensic or preventive point of view. The results of the research can be summarized as follows. After determining the legal basis for the establishment and existence of security companies, the contribution of the relevant international organization as well as the domestic society was also determined in order to determine, among other things, the dynamics of the development of security companies. The work partially studied the activities of two security companies. The importance of the existence and operation of security companies has undoubtedly been established. It can also be argued that different levels of development of security companies can be observed, and that their connection with the economic development of the country in which the security company operates has been observed. In conclusion, the following can be stated. Since the economic system of the Republic of Croatia was developing in dynamic conditions, it was determined that the state system was adapting to newly created expectations, i.e. conditions. This created a consequential effect on the overall economic system of the Republic of Croatia. Certainly, security companies are an integral part of the economic system. Therefore, it can be justified to claim that the development of the 38 economic system of the Republic of Croatia had, and continues to have, a diverse influence on the adaptation and development of the security companies themselves.