Demographic changes, such as those anticipated in most OECD countries, have many economic effects that impinge on a country's fiscal viability. Evaluation of the effects of associated changes in capital-labour ratios and the welfare and behaviour of different generations requires the use of a dynamic general equilibrium model. This paper uses an overlapping generations demographic simulation model, which incorporates bequest behaviour, technological change, the possibility that the economy is open to international trade, and government consumption expenditures that depend on the age composition of the population. The model has been further adapted to study the effects of anticipated demographic changes in Japan, the Federal Republic of Germany, Sweden and the United States. The simulation results indicate that these changes could have a major impact on rates of national saving, real wage rate and current accounts. One of this paper's fundamental lessons is that allowing for general ...