Objective To observe the age-related changes of brain-derived neurotrophic factor(BDNF) and investigate the effects of ginsenosides(GS) on BDNF in nucleus basalis of Meynert(NBM) and cerebral cortex of aged rats. Methods Twenty-four female Wistar rats were randomly divided into 3 groups: young group(3-5 months),aged groups(27 months) and GS group(27 months).GS group was fed with GS from 18 to 27 months.Immunohistochemistry and Imaging analysis were used to show the expression and distribution of BDNF in NBM and cerebral cortex of each group. Results BDNF level of aged group was much lower than that of young group in these two brain areas(P