The purpose of this study is to determine the impact of isolation systems to the seismic response of different types of structures. Once treated the theoretical formulation of analysis, then the application in reinforced concrete structures for buildings is made. The analysis are carried out not only by the linear method, but also by nonlinear methods in order to better analyze the impact of seismic isolation in elastic - plastic response of the structure. Many analyses are performed to different types of based isolated buildings and the comparison between them and fixed - base structures are presented. With analyzing the behaviour of buildings with weak and soft story in case of their seismic isolation, we tend to improve or almost to eliminate their defect. Further, given the fact that the dynamic and seismic response of structures depends not only on external action through the movements of the earth, but also from the characteristics of the structure itself, is studied the impact that brings seismic isolation overall response and specific parameters of structures of different types. Also, are studied the efect of the positions of isolation system in multi story buildings