The aim of this thesis was to propose a model of implementation, enforcement and building of a system of controlling within medium-sized enterprises in Slovakia. In order to propose the system design, we needed to perform an empirical survey in the form of a questionnaire followed by a descriptive and graphic assessment. In the first chapter we deal with the theoretical definition of the concept of controlling and the psychological aspects that affect the individual internal interest groups in the implementation of controlling. In the following chapter we processed and evaluated the results of the questionnaire survey, which mapped the control issues in medium-sized enterprises in Slovakia. In the last chapter of the thesis we have proposed a model of implementation, enforcement and building of controlling system for medium-sized enterprises in the Slovak Republic and we have evaluated the resulting output.