Steadily increasing life expectancy is one of the great achievements of industrialised societies over the last century. Life expectancy has not only been growing among the young and those reaching retirement age, but also, especially in recent decades, among people ages 80 and above. These improvements in life expectancy have led to the emergence of the so-called third age, when people retire, but are still you- ful, healthy and able to participate in society. Nevertheless, closer to the end of life, a fourth age of decrepitude and dependence on others has to be anticipated. - spite the postponement of functional limitations and severe disabilities into higher ages, the debate continues over whether the additional years gained are healthy years, or years with severe care need, particularly among the oldest old, the fastest growing segment of the population. Future improvements in life expectancy and the health status of the elderly will determine the need for care in the future. While different assumptions about these trends based on expert opinion or the extrapolation of past experiences can be made, there will always be a degree of uncertainty about future trends. A third - portant factor driving the extent of future care need is, however, already determined by the history of the past century and is embedded in the age structures of our populations.