The academic literature suggests that the European integration process enhances the development of the economic environment in the case of the candidate countries. The banking sector represents, especially in the case of the new EU member countries, the backbone of the economy, as it is the main channel through which the economic undertakings are financed. Thus, in this context, the aim of our research is to analyse if the ascension to EU membership and the preparation for the adoption of the European single currency, in the case of Bulgaria and Romania, the two countries that have joined the EU in 2007, have determined an enhancement of the overall estimated efficiency of their banking sectors. In order to achieve this we have employed a non-parametric analysis, namely the Data Envelopment Analysis, using one of the most comprehensive samples of banks for this type of researches. The obtained results suggest that during the analysed period of time 2003-2010, the overall estimated banking efficiency for these countries has registered a slight improvement.