The article describes the outcome of the panel survey of the efficiency of the Polish banking sector in the years 1997 - 2002, carried out by means of the Data Envelopment Analysis (DEA).

The aim of the paper is to present the influence of the structural changes in the Polish banking sector upon its efficiency. The analysis is based on three criteria - technical efficiency, efficiency of scale and Malmquist Productivity Index. The above criteria have been estimated by means of the Data Envelopment Analysis (DEA). The method was developed by three Americans: A. Charnes, W. Cooper and A. Rhodes (1978). It is a deterministic method which excludes a random component and does not require a functional relation between input and output.

The research described here is the continuation of the research presented in the article published in "Bank & Credit" No 2/2003, supplemented by data for the year 2002. Additionally, the article contains a comparison of data concerning technical efficiency for Poland and for other CEC5 countries (The Czech Republic, Poland, Slovakia, Slovenia and Hungary). The analysis of the technical efficiency in the CEC5 countries was made using data from the BankScope database.

The results of the survey carried out in years 1997 - 2002 by means of the DEA method show that mergers and take-overs have positively affected the efficiency of the banking sector. The survey reveals that the potential benefit of mergers and take-overs in 2002 did not compensate for the real-sphere influence on the banking sector, nor for the worsening quality of the credit portfolio. This latter factor resulted in a decrease in efficiency and productivity in 2002. The data on the technical efficiency of particular banks show considerable decrease in those engaged in providing credit for large companies. In banks active on the retail market the technical efficiency remained unchanged or even increased. It should be expected that the predicted economic revival should cause improvement in the banks' credit portfolios, which will have a positive effect on the technical efficiency in Poland, as compared with other CEC5 countries. Gradual consolidation on global markets will bring about structural changes in the Polish banking market, but the effects of these changes will only manifest themselves in the future.