In nuclear power plants, major tribological problems can occur among the interacting components, such as those in the control assembly, the reactors and the steam generators, due to a combination of impact and sliding motion. Many experimental wear tests have been performed in either room temperature or simulated high pressure, high temperature water environments to study the effects of materials and various operating parameters on wear. Although several successful numerical models are now available for the prediction of dynamic responses during component interaction, only empirical models having limited practical applications are available for wear damage prediction. In recent years, with the advances in tribology and the availability of sophisticated instruments for metallurgical analysis, there have been attempts to develop predictive wear models based on the more fundamental aspects of wear particle formation and detachment. This review article gives a comprehensive account of the past and present work on wear of power plant components. It also includes a brief review of the general wear processes and wear mechanisms. There are 162 references.