Increases in public debt may have negative effects on many economic variables such as growth, budget deficit and inflation. The increasing cost of borrowing, especially with the emerging uncertainties, leads to an increase in interest rates. On the other hand, increasing interest rates decrease investment rates and result in a decrease in economic growth rates. For this reason, public debt is a very important factor that directly affects the macroeconomic variables of countries through long-term interest rates. The effect of long-term interest rates on public debt is the aim of this study. For this aim, in our study, annual data for the period 1995-2020 were tested with panel data analysis methods to determine the relationship between long-term interest rate, public debt, inflation and economic growth in 15 OECD countries. In this study, no relationship was found between the long-term interest rate and public debt. However, as a result of the causality analysis, a mutual causality relationship was determined between the long-term interest rate and the public debt.