During the 1990s the Italian banking sector experienced a considerable evolution due, first of all, by the accelerating process of monetary and financial integration among the countries joining the European Union. The deep modernization of the credit law contributed to the concentration process and to increase the role played by technical efficiency in valuating banking performance. The aim of this study is to measure the influence of strategic behaviour on banking efficiency over a sample of 551 firms which shows all the peculiarities of the Italian credit sector. The analysis is based on the costrunction of a stochastic cost function in the form of a Translog, considered to be the best in modelling the frontier of an efficient multi-product firm. We followed the intermediation approach which allowed us to emphasize interesting differences of technical inefficiency and to indicate the firm characteristics most important for these differences.