Neurotrophin-3 (NT-3) is a type of neurotrophic factor expressed in the hippocampus. It has been reported that NT-3 was upregulated by stress and corticosterone administration in the hippocampus of adult mice. Since stress suppresses neurogenesis in the hippocampus, we examined whether increasing NT-3 expression suppresses neurogenesis. We also investigated the effects of increased NT-3 expression on mature neuron function and stress-induced behavior. We generated NT-3 overexpressing mice in the hippocampus by administering adeno-associated virus carrying NT-3 gene. Expression of NT-3 in the hippocampus was higher more than 35-fold higher than in the control group. After 4weeks of NT-3 carrying virus administration, the number of proliferating cells and immature neurons in the hippocampal dentate gyrus was decreased in the NT-3 overexpression group. On the other hand, calbindin expression was increased in mature hippocampal neurons. In behavioral experiments, locomotor activity and anxiety-like behavior tended to be increased in the NT-3 overexpression group. These results suggest that high-dose NT-3 may be involved in the suppression of stress-induced neurogenesis and anxiety-like behavior.