AbstractAcquisitions and mergers are the growth and expansion strategies that are commonly used by the companies in all over the world because of several reasons such as increasing the profit, sales and market share, entering into new markets, operating with economics of scale, coping with managerial problems and so on. In recent years, especially in 2005 and 2006, there have been several acquisitions and mergers in the Turkish banking sector. Those mergers and acquisitions have been realized mostly by the foreign banks. The performance of the banking sector in Turkey is analyzed to determine the effects of cross-border bank acquisitions on the Turkish banking sector by utilizing a non-parametric approach DEA (Data Envelopment Analysis).