The studies on seismic isolation of structures gain importance in the recent past because of the loss of life and properties caused by the catastrophic earthquakes on structures. In India, most of the existing structures are under seismic risk due to various factors such as poor construction materials, poor design, and execution, etc. Therefore, the existing structures are to be assessed for their seismic capacity, which would be useful for their strengthening/retrofitting. One of the methods suggested for seismic protection worldwide is seismic isolation of structures. Base isolation is a seismic protection method employed to decouple the structure from the ground motion and reduce the transfer of seismic forces during the earthquake. In this study, two multi-storey Reinforced Concrete (RC) structures are considered, namely, bare RC frame and masonry infilled RC frame for evaluating the effect of the base isolation in reducing the seismic response of the structures. The study utilizes the MATLAB-based numerical model to analyse and simulate the dynamic behaviour of the base isolated RC structures and compared it to the base fixed structures under linear dynamic seismic analysis. The first mode shape of the frames is compared with and without base isolation using the modal analysis. Then the response spectrum analysis as per IS 1893:2016 is conducted by considering the building is situated in seismic zone V with medium soil condition. From the results, it is found that the base isolated structures significantly reduced the seismic responses in terms of design lateral load, increasing the overall seismic resilience of the structures.