There are about 50,000 old dams all over the world operating over 50 years (Jia, 2010). Concrete dams are generally massive structures retaining huge volume of water, failure of which may lead to catastrophic loss of human lives and properties. Environmental issues and the cost of building a new dam are very high, which makes it inevitable to enhance the service life of existing dams. This makes its important to develop a methodology to predict the safety of existing dams and design new dams in such a way that they can have a very long service life. The performance of a concrete dam is further complicated as it is a system consisting of a reservoir, a foundation and the dam itself. Concrete as a building material and construction technology has evolved over the years. Dams undergoing the process of ageing are found to have some distinct symptoms that may cause a chain of events leading to its failure. The foundation below the dam and the reservoir are continued loading may either cause settlement or induce earthquake. In this work, a procedure to predict the dynamic behavior of ageing dams is presented.