Cavitation-erosion is a peculiar form of corrosion or pitting which occurs on the water side of Diesel engine cylinder liners, on hydraulic turbines, on centrifugal pumps and on high speed ship propellers causing extensive and costly damage. As a result it has been the subject of numerous investigations. Despite these studies its mechanism is still unknown although it has been established that the following factors affect the pitting rate of the metals: (a) Hardness, (b) Porosity and surface discontinuities, (c) Viscosity, temperature and molecular size of the contacting liquid, (d) Amplitude of vibration, and (e) the addition of corrosion inhibitors. Some recent experimental data which illustrates some of the above effects is included.