Insurance companies are very important participants in the financial system of any country. One of the most important functions of insurance companies is to insure a person against an uncertain event that may occur in the future. From the point of view of the financial market, the goal of insurance companies is to mobilize and place financial resources. There are 15 insurance companies operating in the Republic of Croatia in the period from 2020 to 2022. The paper presents their position and importance in the financial system of the Republic of Croatia. In the theoretical part of the paper, the basic areas of insurance are presented and the most important terms related to insurance and insurance companies are defined. In the practical part, the activity of selected insurance companies in the segments of life and non-life insurance in the three-year observation period is analyzed and compared. The following insurance companies were analyzed: Croatia Insurance, Allianz Insurance, Wiener Insurance, Generali Insurance and Uniqa Insurance. The business activity of selected insurance companies in the life and non-life segments is analyzed by comparing the data of selected indicators, namely gross premiums, net profit, return on assets and combined scale. According to the analyzed indicators, the most successful company in the non-life segment in the observed period was Croatia Insurance, while in the life segment the most successful was Allianz Insurance. All observed insurance companies were more successful in the non-life insurance segment than in the life insurance segment according to the analyzed indicators.