In the present paper a power- law relationship between erosion rate and cumulative erosion for cavitation has been presented. In order to verify this relationship, erosion tests were conducted in a closed circuit water tunnel in which pure aluminum test specimens were mounted in the wake of cavitating source. Erosion was determined by weight loss on the side wall specimens. The erosion tests were conducted for four sizes of 60⁰ symmetric wedges at wide range of flow velocities and cavitation numbers. The present experimental data confirm the proposed power-law relationship. Moreover, data from various previous investigations of cavitation and liquid impingement devices confirm this relation. The present analysis supports the view that the predominate erosion mechanism appear to be the same in all types of erosion. From the proposed relationship it is possible to predict the magnitude of erosion in a field system with the data from a laboratory device or to predict how much material will be lost in a number of years or how long it will take to lose a certain amount of material for adequate, performance of the component.