This paper explains the concept and significance of public debt in the Republic of Croatia and the way in which it has developed historically. In order to explain the public debt in the Republic of Croatia in more detail, there is an analysis of its relation with the other EU member states. The paper also explains the types of public debt, and its issues, which demonstrate that the amount of debt of the Republic of Croatia at the end of 2020 was HRK 327.8 billion. This paper also presents a strategy that should help manage public debt over a certain period of time, as well as fiscal risks and the macroeconomic framework. Finally, the state guarantee is explained as a potential obligation of the state. The main topic of this paper is the sustainability of public debt in the Republic of Croatia. Methods divided into three basic groups are used to assess the long-term sustainability of public debt; valuation methods using the solvency approach, methods for monitoring the share of debt in gross domestic product, and methods for time series analysis. The conclusion of this paper is that the public debt has its positive and negative components on the overall economic development. Which of them will prevail depends on the amount of debt and its structure. Also, the conclusion is that, without a concrete and high-quality strategy, the public debt can cease to be a problem and be converted into a good opportunity.