A review on¯y ash, an important but problematic waste material is presented. The article deals with several aspects of the characterisation, extraction of metal values leaching and associated environmental pollution problems due to¯y ash. Characterisation includes classi®cation, physicochemical and mineralogical analysis, presence of organic carbon and the signi®cance of cenospheres. Utilisation aspects are con®ned to extraction of metal values and discuss the elemental distribution in y ash while also covering several aspects of leaching including the leaching of speci®c metals. Effect of y ash on surroundings, including ground water pollution and associated problems during disposal, are considered while dealing with the environmental aspects. Some remedial measures are also suggested.