In my thesis, I focused on the issue of the critical infrastructure (CI), the Czech Republic was obliged to implement in its legislation by the January 12, 2011. This was performed by amending the crisis law. The thesis describes generally the critical infrastructure, its history and development in the conditions of the Czech Republic as well as the European Union, the basic legal regulations and it also characterizes the concepts associated with this issue. In the scope of the research I focused on comparing the fields of CI, changes in criteria and principles of determining CI elements and influence of these changes on the number of the subjects of critical infrastructure in the South Bohemian Region. As it turned out during the elaboration, it is not simple to find out the newly established numbers of CI subjects.