The data presented clearly show that piracetam protects mitochondria against different conditions associated with oxidative stress including aging. Piracetam's protecting effects on mitochondrial damage induced in vitro are small, but reproducible and highly significant. This is not surprising, since the conditions used to induce oxidative stress in vitro are not pathophysiological but rather aggressive, in contrast to the small and slowly occurring changes induced by aging, which however were sometimes completely reversed by piracetam treatment. This was also the case for the adaptive elevation of antioxidant enzyme activities. When mild conditions were used in vitro (e.g. partial serum deprivation), a complete protection of mitochondrial function was seen by piracetam treatment in PC12 cells. Moreover, piracetam was highly effective in vivo in pathophysiologically relevant situations of brain dysfunction.