Conventional dichotomy or three-part classifications for disease and age are not very helpful for practical application. The article presents a typology of disease, which we developed further into four categories. It considers the relation between physiological processes of aging and pathological developments as well as the courses of disease in old age. Adequate prevention strategies can be derived. Category I (physiological changes in old age which are only possibly a disease) demonstrates the importance of the context in illness. Physiological processes of aging with a high plasticity can be influenced by prevention strategies. Category II (age-related disease with a long latency period) demonstrates the problem of early recognition and secondary prevention. The category III (disease with different physiological process in old age because of reduced homeostatic regulation and repair mechanism) is not receptive to preventative concepts, but only to tertiary prevention and rehabilitation. In the category IV (disease as a result of long term exposure, increasing with lifetime) population-based prevention strategies are sensible.