In the 21st century tacit knowledge and its management has become a central theme of organizations and enterprises. Until the last decade, the possession of physical resources meant wealth and power in business. Labour, capital and natural resources were the key factors of production. Today, this trend is undeniably changing. In the rapidly evolving world of technology the only important factor providing long-term competitive advantage is the knowledge of the employees. Tacit knowledge is an invisible resource which has an enormous effect on the performance and success of a company, though it is personal, context-and cultures-pecific, besides hard to formalize and communicate. Tacit knowledgeincludes experiences, ideas, values and emotions and of course the factors of national culture. The main problem is that institutions are not aware of what kind of knowledge and information they possess. Hence, these assets are unorganized and not focused towards any objectives. The difficulties of sharing the lessons and experiences lead to wasting time and money on solving problems that have already been solved. That is why it is necessary to engage in knowledge management. As part of a wide-range research, we have examined which methods and procedures are used by Hungarian and Slovak companies to facilitate the retention of tacit knowledge of their employees in the organizational memory. How can the national culture influence the use of tacit knowledge management methods? The study involved 124 Hungarian and 122 Slovak companies and raised important questions in the scientific and organizationallife as the focus of our research. In our research we aspired to involve a wide range of enterprises, subsequently we examined small-and medium-size enterprises, multinational companies and organizations from both the for-profit and non-profit sectors. We conducted both qualitative and quantitative research because this is the most effective way of understanding the problem mentioned above.