The present study has employed a multiple-stage approach based on Data Envelopment Analysis (DEA) to measure the level of efficiency and productivity of the Australian banks before, during and after the Global Financial Crisis 2007-2009. The purpose of this analysis is to: (i) measure and compare the efficiency level of banks applying three different approaches; (ii) measure productivity changes of the sample banks by the means of the Malmquist indices; (iii) assess the relationship between the level of efficiency and the institutional size of each bank by the means of a univariate cross-tabulation approach; (iv) examine the impact of the global financial crisis 2007-2009 on the performance of Australian banks; and (v) analyse the competence of recent mergers and acquisitions in Australian banking sector in the performance of banks.