Recent swings in fertility rates, combined with anticipated increases in life expectancy, are expected to result in a significant increase in the number and proportion of elderly persons in the first half of the next century. This "ageing" of OECD populations is expected to have widespread impacts, affecting labour markets, the composition and level of consumption and output, national rates of saving and the rate of capital accumulation, etc. A widely recognized effect of ageing will be the pressures it will place on public sector finances as the share of future output transferred to a large dependent population rises. This paper discusses some of the potential economic impacts of ageing. It also presents an analysis of its impacts on public pension financing requirements, with particular emphasis on selected OECD countries -- Germany, Japan, Sweden and the United States. It is shown that, where desirable, future increases in retirement age and benefit reductions could help reduce ...