Regarding the increasing importance of buildings in different parts of the world, the damages from earthquake in an area are increasing. Base isolation is an important solution in decreasing both floor displacement and floor acceleration. Depreciating a large amount of the dynamic energy transferred from earth to structures, isolators reduce the resulted forces from earthquake [1]. In this study, the performance of these isolators in decreasing seismic response is investigated. The software SAP2000 is used to conduct the dynamic analyses of time-history in seven earthquake pairs. Four buildings with 3, 6, 9, and 12 floors were modeled and the effect of isolators on the parameters of base shear, superstructure torsion and relative displacement of floors has been investigated. The results from the conducted analyses represent appropriate performance of isolator systems in plan and height if irregular buildings [2].