A structure is considered to be irregular if it exceeds the code limits of prescribed irregularity as per IS 1893: 2002. The previous earthquakes show that these structures have failed considerable. However, these structures are very useful and can be used for creating basements and open spaces in bottom storeys. In this research work, different types of irregularities like mass, stiffness and strength have been discussed. In the first section, the different type sof existing irregular buildings have been presented and in subsequent sections seismic response of irregular buildings have been studied. This research work aims to study the effect of these irregularities on seismic response and to propose new alternative rules to code proposed rules in determination of seismic behavior of structures. Finally, the applicability of the proposed equations in recent methods of seismic design is also discussed.