Purpose of the article: There are many a studies by universities and various companies regarding the phenomenon of family business. However, a clear interpretation of the family business does not exist. Thus, the purpose of this paper is clarify the question of family relationships existing within the family business in the Czech Republic. Methodology/methods: As the wine family business is a bright representative of the oldest and traditional economic activities, it was decided to analyze the family relationships of 108 representatives of the wine family firms in the Czech Republic within the secondary research. For primary research the case study method was used. Representatives of wine family firms were interviewed to confirm the obtained results and add the details. Scientific aim: The aim of scientific research is to improve the understanding of family firm's base from the perspective of family relationships. Findings: Coming out of the definition by Arquer (1979) and taking the applicable Civil Code of the Czech Republic into account, the author has created a definition regarding the family business to be transferred to the next generation. Accordingly, there were identified four dominant groups of family relationships within the wine trading family business. A representative interviewed among others has confirmed the existence of traditional wine trading family business saying that it is not only a mere marketing tool for the customer acquisition. Besides that, case studies make clear beyond the veil the influence of family relationships on the firm's performance. Conclusions: This study has contributed to the theoretical body of family business research providing an important first step to gaining insights into the understanding of family relationships of the family business influencing its effective functioning.