A significant contribution to the development of high performance, high specific output automotive engines with extended durability comes from improvements in valve gear efficiency. This paper attempts to review the factors which contribute to valve gear friction and wear and influence its reliable long term function. The roles of the type of valve gear, component design factors, materials, and surface finish in determining the effective stresses and subsequent wear modes under dynamic conditions are discussed. Environmental factors, such as lubrication, corrosion, and temperature, which influence valve gear distress are also outlined. Future trends in seeking new materials and processing for designing lighter, lower friction, extended durability, and higher performance valve gear are suggested. Methods of evaluating new materials, and designs for predicting their wear performance and durability, are also presented.