1. The cavitation resistance of OTsS 6-6-3 bronze used for components of hydraulic press valves is very low; this alloy should not be used for parts exposed to cavitative action. The low resistance is due to the low strength of this alloy and to the fact that its structure contains lead inclusions. 2. Of the Cu-base alloys tested, the Br. AZh 9-4 bronze, the LK 80-3L silicon brass, and precipitation hardened Br. B2 bronze, have the best cavitation resistances. Br. AZh 9-4 bronze has about the same cavitation resistance in the cast as in the pressed states. 3. The cavitation resistances of different alloys depend on their microstructures. Dispersed intermetallic strengthening phases and a number of other structural features have been found to exert a good effect on cavitation resistance. 4. A secondary method of studying the structural features of metals and alloys is to test them by magnetostrictive vibrator.