SUPUKOVÁ, Zuzana: Differences in corporate culture in small and medium-sized enterprises over time [Diploma thesis] - Technical University in Zvolen. Department of Economics, Management and Business. Diploma thesis supervisor: Ing. Silvia Lorincová, PhD. Degree of academic qualification: Engineer, abbr. ,,ING.“. Zvolen: TU, 2020 Corporate culture is an important prerequisite for the success of the company and for achieving positive results. It is a phenomenon that regulates workplace relations, creates a regulatory function and strengthens the meaning of employment. The subject of this thesis is issues in the field of corporate culture. The theoretical part of the thesis defines the concepts of culture, resources, elements, strength, functions, types of corporate culture and change, with a more detailed focus on the methodology of Cameron and Quinn. The practical part of the diploma thesis is focused on the comparison of corporate culture in Slovakia in the year of 2017 and 2019 and the comparison of its current and future levels through the OCAI questionnaire (The organizational culture assessment instrument). The aim of the thesis is to define the differences in the corporate culture of small and medium enterprises over time. The results show that in small companies in Slovakia, the clan corporate culture prevails, which is characterized by features such as a friendly work environment or a family-type atmosphere. In medium-sized companies, a hierarchical corporate culture prevails, characterized by its formalized and structured work environment emphasizing procedures and regulations, in which formal rules are the unifying element. We identify with the achieved research results. We recommend small businesses in Slovakia to apply a clan corporate culture. In our opinion, this is the most suitable type of corporate culture, especially due to the smaller number of employees, where people are often in contact with each other. We encourage business management to consider teamwork and participation as paramount. Employee knowledge and experience or new creative problemsolving ideas should be a clear advantage over the competition. We consider a hierarchical corporate culture to be the most suitable for medium-sized companies, due to the size and higher number of employees, where hierarchy is especially important. We recommend that mediumsized companies consider performance, control and stability to be paramount. Well-managed logistics and reliable deliveries should be an advantage over the competition.