Seismic waves which are formed during an earthquake carries enormous force that transfers to the base of the structures in different directions. Due to this, the building structure undergoes drastic changes in existing stresses and strains. Mechanisms that are responsible for the damages in structures during an earthquake are acceleration of floors and inter story drift. The traditional ways of resisting the foresaid force are shear walls, moment resisting frames and braced frames etc. It is documented frequently that; the traditional methods are not completely effective to absorb the earthquake force. Therefore, Seismic isolation concept is an effective rehabilitation strategy that is in practice now and gives favorable results. In this work, 6 x 3 Bay with 14 Stories (G +13) RCC building structure incorporated with Lead Rubber Bearing (flexible base isolation) and fixed base have been modeled and analyzed for earthquake force along with other active forces using FEM program. The structural quantities, time history investigations and response spectrum examinations have been compared for both base isolation and fixed base models. It is found that the technique adopted decreases the seismic response considerably compared to conventional (fixed base) structures which intern controls the damages in building. Bases shear and floor accelerations have been reduced but displacements increased in isolated base when compared with fixed base.