Analyzing the topic of this thesis, the author tried to explain and analyze the structure of capital in Croatian companies. The decision on how to finance a company is a key decision in every company. The aim of this thesis is to present theories about the structure of capital, to show key factors affecting the structure of capital in companies of Republic of Croatia and to determine which theories were led by managers of Croatian companies. The work consists of two parts. The first part of the thesis, elaborates the financing of the company, defines the sources of funding, the business objectives of the company, represents the theory of the capital structure and defines the differences between different theories of the capital structure. In the second part of the thesis, the author analyzes the structure of Croatian companies using six different financial indicators: indebtedness ratio, financial strength indicator, financial leverage index, debt share in financing, ratio of total debt and equity and interest coverage of the operating profit observed over three years. The author of this thesis wanted to further clarify the theory of the capital structure and hopes that with this analysis he helped to understand the structure of capital in Croatian companies.