Nowadays, about the half of Swiss women die after their 84th birthday. This unprecedented proportion of the population reaching an old age, or even a very old age (25% of women die after 89 years, and 5% after 95 years) is a novel aspect of human demographics, and represents the very last stage of the epidemiological transition, a term coined to describe the transformation of the prevailing health burden in the population, shifting from infectious and communicable pathologies to chronic and degenerative diseases. In developed countries, this epidemiological transition has been well documented during the last century; worldwide, a similar transition is taking place, with some countries still at mid or early stages of transition. A striking aspect of the current transition is its speed. In India, the mean duration of life since 1947 has increased from 32 to 62 years. As a result, India, like many other developing countries, is facing a double burden of disease, i.e., an upsurge of degenerative diseases while the burden from the old agenda (i.e., malaria, tuberculosis) still reaches devastating proportions in the population. This double burden is certainly a crucial problem in developing countries, and probably is the most important health challenge for the coming century. A similar accelerated pace of change is observed with the decline of mortality at old age. Worldwide, the current estimate of centenarians is 100000, i.e., ten time more centenarians than the number estimated in 1960. The downward trend in mortality, which is steeper with increasing age, is now the leading factor to Increase the life expectancy in developed countries. In the United Kingdom, life expectancy increased by 2.5 years between 1971 and 1991; this is equivalent to the increase observed between 1851 and 1961. This accelerated increase will influence public health in two different ways. The first will be the absolute increase in the number of older persons, with a corresponding increase in degenerative diseases. A second consequence will be the need for a substantial and rapid adaptation of the health care system. Three selected aspects are addressed below: 1) the increase of resources, 2) the improvement of performance, and 3) the reduction of demand through preventive strategies.