In this research, seismic fragility analysis of storage tanks is carried out with a large damage database from past earthquakes and analytical studies. At the fragility analysis, a new damage state has been defined. Peak ground acceleration is employed as an intensity measure. Epistemic and aleatory uncertainties are considered. At the observational fragility analysis, logit, probit and cumulative lognormal model and maximum likelihood method are utilized. In this research, Finite Element Analysis is also performed. As a result, new seismic fragility curves for storage tanks obtained and compared with the existing tank fragility curves in the literature.