In this work, we propose to evaluate bank efficiency in Argentina using DEA Method (Data Envelopment Analysis). This study is based in private bank entities for years   1998 -  2004, a particular period of time in which openings and closures were produced (either because of merger or acquisition of several banks). As their continuity in time is known, and using the obtained results of its performance, it is interesting to analyze if there is any relation between  efficiency and permanence of those banks in the market.