Our study aims at measuring banking system efficiency for France and WAMU, by isolating environmental specificities to each region. Our results show that the two banking systems have quite close efficiency scores about 80%. As their french counterparts, WAMU banks are efficient; however this assertion is true in regarding the environment in which they evolve. Indeed, those banks transform collected deposits in short term loans or loans to big foreign corporations, that they are sure to recover lent amounts. This situation has the following effect: a significant part of entreprises (smal and medium ones) are under funded. The comparison of the two banking systems lead us to suggest that monetary and financial authorities implement reforms. Those reforms inspired by french ones and adapted to the WAMU specificity and environement, would help the banking system of the zone to effectively play its financial intermediary role.