This paper devoted to the mass and volume losses of metals subjected to cavitation. It studies the Relation between the Cavitation index, operating condition, time elapsed and the mass loss. Three venturies with different throttling area were used to generate cavitation. Aluminum sheet (0.9 mm) and stainless steel sheet were subjected to the cavitation and they were weighted before and after the experiment using 0.001 accuracy Balance. Using the curves in this paper, the life time of the alloy can be predicted. During the experiment the mass loss increased by 25 % when the Cavitation decreased by 30%. And the effect of material hardness and Reynolds number was studied.