An analytical study has been carried out to investigate the seismic behaviour of multi-storey buildings resting on normal and sloping grounds in different seismic zones with and without base isolators. Totally 160 multi-storey building models with rectangular configuration in plan of 12 x 16 m size have been analysed. The building models considered ranges from 1 storey height to 10 storey heights, and assumed to be located in seismic zones II, III, IV and V as per Indian standard code under two different terrain conditions viz. plain and sloping grounds with and without seismic base isolators. Response spectrum method of dynamic analysis has been performed using STAAD Pro software for all the building models, and the dynamic response quantities such as fundamental time period, base shear, top floor displacement and inter-storey drift were obtained for all the models. Seismic analysis results of building models indicate that for a given seismic zone and terrain condition, the introduction of seismic base isolators at base level of building increases fundamental natural time period, but reduce base shear, top floor displacement and inter-storey drift of the building. The results also indicate that for a given base (i.e. support) condition and terrain nature the base shear, top floor displacement and inter-storey drift increase as the seismic zone level increases. Furthermore, the results indicate that the introduction of seismic base isolation system at the base of building makes the structure behave like a rigid structure.