The seismic performance of liquid storage tanks has been a matter of special importance, beyond the economic value of the structure, due to the requirement to remain functional after a major earthquake. Water supply is essential immediately following destructive earthquakes, not only to cope with possible subsequent fires, but also to avoid outbreaks of disease. Another reason is the potential danger associated with the failure of tanks containing highly inflammable products, which can lead to extensive uncontrolled fires, while possible spillage of such contents might cause extensive environmental damage and affect populated areas. the seismic responses of base-isolated cylindrical liquid storage ground as well as elevated tanks are investigated. Three types of isolation systems are considered. The responses of broad and slender tanks are obtained. The seismic responses are compared with the corresponding responses of non-isolated tanks. It was found that, base isolation is quite effective in reducing the earthquake response of ground and elevated liquid storage tanks.