The effect of frequency content on the dynamic response of concrete gravity dams is investigated in this paper. Dams are one of the most complex structures to handle when there is dynamic analysis involved. One of the influential parameters on these structures' seismic response is the frequency content of the earthquakes. An index to represent frequency content, which represents frequency content by PGA/PGV ratio(FCI) and sets three ranges including high(FCI>1.2), intermediate(0.8