Nowadays, insurance activity gets more and more important. By studying any activity, it usually starts from its basics. Therefore, this work begins with the insurance activity as part of the financial system. Consequently, we come to the cause of the insurance, its role and the functions it carries out. Below are listed non-life insurance, life insurance and complex insurance (combined with the previous two insurance). By performing them, the insurance companies earn a gross premium. In this way, insurance companies are obliged to prepare financial statements and publish them publicly. The information and data in the financial statements must be true and timely. In order to understand the theoretical part, three Croatian insurance companies will be selected and their performance will be determined on the basis of their financial statements. Thus, a comparative analysis of the financial statements of the three Croatian insurance companies will be practically carried out. They will carry out a horizontal analysis of the balance sheet and profit and loss account of each individual insurance company. In order to obtain a complete picture of their business, the analysis of the balance sheet and the profit and loss account will be performed by means of indicators groups. After the analyzes carried out, a conclusion will be reached. The conclusion will provide an objective opinion on the business of each individual insurance company and provide a formula for successful business operations. There will also be new discoveries that may have impact on the further work of insurance companies. The work will be completed with a list of literature, tables, pictures and graphs used in the design.