Purpose-The aim of this study is to empirically investigate the relationship between the change in exchange rates and the profitability of firms in Turkey. The changes in real effective exchange rate as the change in exchange rates criteria and return on assets as well as return on equity are considered for measuring profitability. Methodology-The sample of the research consists of 37 companies that are listed in BIST 100, operating in the manufacturing sector and whose data can be accessed completely. The data of the companies within the scope of the research were obtained from the official websites of Borsa Istanbul, Public Disclosure Platform, and Finnet and made ready for analysis. For the purpose of the research, panel data analysis, panel unit root tests, panel regression analysis, causality analysis, and moderating effect analysis were carried out. Findings-. Changes in foreign exchange rates, foreign sales and asset size of the companies do not have any significant impacts on the return on assets and return on equity during the period between 1999-2019 in Turkey. It has also been found that asset size, foreign sales, and change in exchange rates are the reasons for the return on assets and similarly, asset size, foreign sales, and change in exchange rate are the reasons for the return on equity. Finally, changes in the foreign exchange rate and export sales have a short-term causal relationship with both return on assets and return on equity, and changes in the foreign exchange rate and total assets have a moderating effect on return on assets. Conclusion-As a result of the research, it has been revealed that firms are affected by changes in foreign exchange rates with a delay. It means firms were likely be affected by the changes in exchange rates with a lag, and similarly, the changes in exchange rates affected financial performance with a lag. It has also been revealed from the research that firms effectively use internal and external hedging methods that help reduce the adverse impacts of the changes in foreign exchange rates.