Objective: To investigate the effects of cornel iridoid glycoside (CIG) on neurogenesis in adult rats. Methods: Adult Wistar rats were randomly divided into groups, and treated with i.g. CIG (60 and 180 mg·kg-1) or distilled water (normal control) for 26 days. Thereafter, BrdU was intraperitoneally injected into the rat, 2 times a day for 3 days. The brain was isolated at 24 h and 28 d, respectively. Immunofluorescence assay was used to detect the expression of BrdU-labeled neural stem cells (NSCs) in the hippocampal dentate gyrus. Double immunofluorescence labeling was applied to detect BrdU/Map-2 labeled mature neurons differentiated from NSCs. Results: Compared with the normal control, the number of BrdU-labeled cells in hippocampal dentate gyrus was significantly increased in CIG-treated rats at 4 days after BrdU labeling (P<0.01). The number of BrdU/MAP-2 positive cells was obviously elevated in CIG-treated rats at 28 days after BrdU labeling (P<0.05 and P<0.01). Conclusion: CIG is able to promote the proliferations and differentiation of endogenous NSCs in hippocampal dentate gyrus of adult rats. ©, 2015, Chinese Journal of New Drugs Co. Ltd. All right reserved.