This paper is focused on the indicator of WACC in the conditions of SMEs in the transitional economy in the Czech Republic. The behavior of SMEs in connection with the capital structure is described as specific, with a special features rooted in the national economic conditions. The research question is what is the typical model of capital structure of these companies in the Czech Republic and if there are differences in the individual section of SMEs, i. e. in micro, small and medium companies. The research is based on the set of three hundreds of Czech small and medium companies, data of which were derived from the database of Albertina. The results confirmed the findings of previous research: the main part of the firms´ capital is formed by the equity. The share of foreign resources is composed primarily of trade payables. Indicator WACC thus reflects mainly costs of equity in a concrete branch and company.