A review on fly 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 fly ash. Characterisation includes classification, physicochemical and mineralogical analysis, presence of organic carbon and the significance of cenospheres. Utilisation aspects are confined to extraction of metal values and discuss the elemental distribution in fly ash while also covering several aspects of leaching including the leaching of specific metals. Effect of fly 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.