[Old age, normality versus pathology].

Since life expectancy of Brazilian population increased and aging was considered a "social problem", there has been a boom of specialists in old age. Gerontologists and geriatricians are now playing a relevant role in setting new trends to the management of issues related to old age. However, gerontology as a field of knowledge seems to have internal questions that apparently hinder its professional consolidation and its scientific recognition. In this article, the author focus the difficulties gerontology has in order to delimitate its field of action and to define the object of its studies. The author argues that such difficulties derive from a central point: the impossibility to delimitate the frontiers between what is normal and what is pathological in old age. He also analyzes the constitution of medical knowledge on aging in a historical perspective.