In this study, the factors determining profitability in the Turkish banking sector are examined. Return on assets (ROA) is analyzed through panel data analysis using internal, external and sectorial factors. The purpose of the study is to explore the factors that affect bank profitability and to develop policy suggestions based on the findings. In the literature section of the study, domestic and foreign sources concerning bank profitability are scanned. In the section of econometric analysis, data belonging to the period 1990-1999 of state-owned, privately owned national and foreign deposit banks operating in Turkish banking sector are analyzed by using Stata program and panel data method. The analysis results indicate that capital and liquidity are the most important variables for ROA.... In addition to that, it is reached that it is ensuring the efficiency in cost management for 1990-1990 period, keeping loans under follow at a low level and risk management make a positive impact on profitability.