The Seismic behavior of buildings critically depends on its overall shape, size, and configuration. Buildings with re-entrant corners in plan are considered to be irregular by many seismic design codes. The seismic behavior of RC buildings with symmetrical floor plan shapes having re-entrant corners (H shape, + shape) is investigated in this paper. Various types of building plan configurations with increasing amount of irregularity (A/L ratio) as per IS 1893 code are modelled and analyzed using ETABS 2015 software. A regular plan building is also modelled as a bench mark problem to compare all irregular models. Response spectrum analysis has been carried out for all these models located in seismic zone V of India. Various dynamic parameters such as Story displacement, Story drift and Base shear are compared and some useful conclusions are drawn.