This paper analyzes the sustainability of the existing pension system of the Republic of Croatia. The topic is current and arises due to the worsening demographic structure of the population in the Republic of Croatia. The pension insurance system is an extremely important part of social care aimed at reducing the risk of poverty among the elderly population. The Croatian pension system consists of two main pension pillars, intergenerational solidarity and individual capitalized savings and one voluntary pillar. Contributions paid into the first two pension pillars are paid by current employees and serve to pay the pensions of current retirees. The sustainability of the pension system has been a pressing problem in Croatia for years, for which no effective solution has yet been found. The aforementioned situation is favored by thedemographic picture of Croatia, which for decades has been characterized by a decrease in the total number of inhabitants, the growth of the elderly population, the increasingly frequent emigration of young people and low fertility rates. The above has a strong negative impact on the sustainability of public finances, the labor market and the overall image of the Croatian economy. The projections of the National Bureau of Statistics and Eurostat are very worrying. If they turn out to be correct, at the end of the century Croatia will have a much smaller number of inhabitants than now, the structure of the total population will take the form of an inverted pyramid, and there is a great possibility that the population will change. In other words, with the import of cheap labor and the settlement of foreign workers, the Croatian population will eventually no longer be so dominant in its own country. It is necessary to carry out quality pension reforms. In order to implement the necessary reforms, it is crucial to identify the main threats to the pension system and possible opportunities for its improvement.