This study presents the effects of Turkiye's external debt on economic growth and is examined with Markov Regime Switching Models, unlike previous studies, considering that Hamilton's (1989) regime-switching models are a very powerful tool for modeling non-stationary time series. In this study, annual data for the period 1970-2020 were used for the Turkish economy. Countries use external borrowing to achieve economic growth and development objectives. However, the effect of external debt on economic growth is still debated in the literature. The vast majority of empirical investigations have shown that external borrowing has a negative impact on economic growth. In the analyses, the 1970-2020 period of the Turkish economy was divided into three periods, which can be named growth, crisis, and precrisis periods. Analyses show that only the coefficient of the gross external debt stock variable differs in the obtained regimes. According to the results of the analyses, it is seen that the gross external debt stock has a negative effect on Turkiye's economic growth in all regimes, including the growth period, while the gross fixed capital formation, export, and population have a positive effect