The present study represents part of a research effort having the objective to correlate cavitation with the associated hydraulic turbine erosion and associated performance degrading. The present analysis concentrates on field studies carried out in a large hydroelectric plant with the use of Acoustic Emission monitoring which is associated with turbine running parameters. Three identical Francis turbines but presenting different stages of wear have been considered in the present text. Initial analyses of the problem show that there is a clear association between acoustic emission average signals obtained during standard loading and the degree of turbine blade wear.