In this study, efficiency of the banks carrying on their business in Turkey in 2009-2011 periods has been measured. Data Envelopment Analysis which is one of the non-parametric methods has been used to measure the efficiency. Moreover, factors that are considered as possible to affect efficiency scores of banks have been determined with TOBIT regression analysis. Totally 37 banks data of which could be reached exactly have been included in the research. According to Data Envelopment Analysis results, the group of bank that has the highest average efficiency is state-owned banks, followed by privately-owned and foreign banks. According to TOBIT regression analysis results, total assets and profitability variables have a positive effect upon total efficiency scores, but capital adequacy ratio and number of branches have a negative effect. …