Resumen
The objective of this research is to examine the relationship between market structure and the performance of the Tunisian banking system over the period 1990-2009. The Data Envelopment Analysis (DEA) method was used to assess the scores of x-efficiency and scale efficiency, the hypotheses of the market power theory and those of the efficient structure theory were tested. Our Results have shown that x-efficiency has had a positive and significant effect on the performance of the Tunisian commercial banks as well as the hypothesis of x-efficiency.