Aging alters progressively all aspects of health. Physical health is affected by physiological aging that impacts on all tissues and organs, notably sensorial systems (hearing, sight), the locomotory and the immunological systems (lowering of resistance to infections). There is an increase with age in the incidence of many cancers (particularly breast, prostate, and colon cancers) and cardiovascular diseases. Regular check-ups are useful in order to take appropriate measures in time. It is important that people maintain regular physical activity and a balanced diet even up to an advanced age and the elderly must learn to adapt themselves to the ever-changing abilities of their organism. It is possible to slow down the aging process through good hygiene and often to maintain autonomy until the end of life. Mental health is threatened by impairment of mental functions, depressive tendencies, and the risk of senile dementia that cannot be foreseen or avoided. It appears that keeping intellectually active and having a good level of education impact favorably on mental aging. Social health depends, for a large part, on the way society accepts and treats the elderly. They must be kept integrated into society and allowed to live at home for as long as possible. Any measures of rejection, discrimination, and exclusion should be opposed. The dignity of the elderly must be respected and activities giving them a feeling of usefulness should be encouraged. It is important to help families who care for their parents at home, to develop and evaluate healthcare networks, and encourage medical professionals and social services to work together. The change in the demographic structure of France is a considerable phenomenon requiring a long-term strategy and not only superficial and cosmetic measures. To cite this article: M. Tubiana, C. R. Biologies 325 (2002) 699-717. © 2002 Académie des sciences / Éditions scientifiques et médicales Elsevier SAS aging / aloneness / autonomy / dependence / discrimination / exclusion / geriatric / gerontology / life expectancy / mental health / public health / quality of life / social healthRésumé -Le vieillissement altère progressivement tous les aspects de la santé. La santé physique est atteinte par la sénescence physiologique, qui touche tous les tissus et organes, notamment les systèmes sensoriels (ouïe, vue), le système locomoteur, le système immunologique (baisse de la résistance contre les infections). On observe aussi une augmentation avec l'âge de la fréquence de nombreux cancers (notamment sein et prostate, colo-rectaux) et des maladies cardiovasculaires. Des bilans réguliers sont nécessaires pour prendre à temps les mesures utiles. Il faut maintenir une activité physique régulière et une alimentation équilibrée jusqu'à un âge avancé et habituer la personne âgée à s'adapter aux capacités constamment changeantes de son organisme. Il est possible, en observant des règles d'hygiène, de ralentir le processus de vieillissement et souvent de maintenir une autonomie jusqu'à la période ultime ...