Abstract: Dam safety is related to the physical condition of a dam structure,which in turn is governed by maintenance and rehabilitation work.The latter activities control,to a certain degree,the life-span of the dam structure.Benefits derived from dam safety activities depend largely on the investments made in maintenance,monitoring and surveillance.In the first part,this paper discusses the impact of issues like ageing,maintenance,vulnerability,and design requirements of both concrete and embankment dams and their foundations on their possible life-span.In the second part,the benefits of investments in safe dam design and in dam safety activities,like maintenance and monitoring,are evaluated.It is shown that the return is not directly in monetary gains but in safe and mostly trouble-free operation,preservation of the investment made in the original structures,prevention of the financial consequences of a dam failure,improved public awareness,and risk-free activities in the downstream area.