The pollution of the environment and the associated ill effects have become cause of serious concern due to advancement in science and technology and industrial revolution, whose nature and character is changing with each major development. The requirement of the electrical power has forced the humans to exploit all possible sources which include hydroelectric, thermal, solar, wind, nuclear etc. Also, different industries viz. fertilizer, sugar etc. require coal. Thermal power plants and these industries produce huge quantities of fly ash which creates serious environmental degradation and health hazards besides affecting the land fertility and crop productivity, if not properly disposed off. This waste material can be used effectively in construction industry to overcome the problems cited above besides resulting, in general, in safer, economical and durable structures. The various uses to which fly ash may be put are structural concrete, mass concrete, roller compacted concrete, masonry works, soil stabilization, manufacturing of precast concrete building units, water and wastewater treatment and land reclamation etc. In this paper, the sources of fly ash production, its uses in construction industry and economical aspect of its use are presented.