The behavior of the building mainly depends on its overall shape, size, and geometry in the event of an earthquake. As irregular floor plans are more vulnerable to earthquakes, they are not recommended in seismic prone regions, but still widely used everywhere. In this present study, the seismic behavior of RC buildings is analyzed using linear dynamic Time History Analysis considering the Olympia (1949) earthquake ground motion data as input. Various RC buildings with different floor plan shapes having re-entrant corners (L, C) with increasing amount of irregularity in terms of A/L ratio are considered for investigation. The various response parameters, such as base shear, story drift, and top storey displacements are observed and some useful conclusions are drawn. For the present research, ETABS 2015 [1] software has been used as modeling and analysis tool.