The pension system is a central instrument of any society, that is, of any country that wants to provide financial security to its citizens when they are no longer active in the labor market or do not belong to the labor force, as well as in case of health problems such as disability and others. The basis of the pension system is precisely the working-age population, which largely ensures the funds for further distribution. Moreover, the demographic structure of the population is of great importance, and it is not favorable. The gap between the generations of the working population and pensioners is widening, which is why part of the pension system is financed from the state budget. The aim of this paper is to explain in more detail the concept and functioning of the Croatian pension system, to show its evolution and to describe the factors that influence it. It also aims to present the functioning of the Croatian pension system and compare it with the selected countries of the European Union, namely Germany, the Netherlands and Ireland, where the migration of the Croatian population has been recorded. The information on the number and structure of the funds and the members of the funds, the distribution of assets and the movement of the index MIREX were analyzed. The comparison of Croatia with selected countries is presented based on the analysis of the distribution of assets and the limitations of the portfolio in the investment of pension funds. From the comparison it can be concluded that the characteristics of the Croatian pension system are very similar to the pension systems of the observed countries. Moreover, when comparing the percentage of distribution of pension fund assets among specific categories with total investments, Croatia does not differ significantly from the observed countries, and there is no difference in portfolio constraints on pension fund investments.