This review of present knowledge of pitting corrosion of copper and its alloys is restricted to what is sometimes described as nodular pitting. By this is meant localized corrosion producing small areas of deep attack covered by small mounds or nodules of corrosion products. It excludes localized attack due to the combined effects of corrosion and erosion (impingement attack) and cavitation damage, such as occurs under very high water velocities on parts of marine propellers and pump impellers. The major part of the paper is concerned with nodular pitting of copper in fresh waters; pitting of copper alloys and pitting of copper in sea water are dealt with more briefly.