As we know that large population in the world are living in regions of seismic hazards, at risk from earthquakes of varying severity and frequency of occurrence. The significant loss of life and damage of property occurs every year due to earthquake. Here the one of the best solution to mitigate the effect of earthquake on building is base isolation technique. The main mechanism of seismic isolation is to decouple the structure from base by providing seismic isolators. The Lead Rubber Bearing (LRB) is mounted beneath the superstructure in base isolation system. The significant of base isolation device is to minimize the horizontal acceleration transmitted to the superstructure. It is very promising technology to protect different structures from seismic excitation. In this research, GF+4 storied regular, plan irregular (re-entrant corners) and vertical irregular (vertical geometric irregularity) building models were considered for both fixed base and base isolation in SAP. Response spectrum method analysis under IS1893:2002 was conducted in analysis software for the result of seismic performance parameters. The output results of seismic parameters were interpreted and compared. The SAP analysis results were compared and validated by ETABS software. Lead rubber bearings were designed as UBC 97 and used for base isolation. The research concluded that, Plan and vertical irregular LRB building found more seismically performed than regular LRB building however vertical irregular LRB building showed better performance as comparison to plan irregular LRB building.