This paper analyzes the evolution of competition in the Tunisian banking sector in the period 2000 - 2008, which is a period of deregulation, liberalization and consolidation of the sector. For this purpose, we use two indicators of the competition from the theory of the industrial organization (the Lerner index and the Panzar and Rosse’s H-statistic). The empirical evidence does not permit us to reject the existence of monopolistic competition. The evolution of Lerner index over the period of study shows a low tendency to concentration. The movements of the mergers of the banking institutions seem to be slow, as a big effort of cleaning their balance sheets remains to be achieved before banks can merge.