P>Objective To study the neurogenesis of the dentate gyrus (DG) and the expression of the doublecortin (DCX) in the hippocampus of the rat whose spatial learning and memory function was enhanced by chronic multiple stress. Methods Adult male Wistar rats were randomly divided into two groups: multiple stressed group and control group. Rats in the multiple stressed group were irregularly and alternatively exposed to the chronic multiple stress for 6 weeks. After that, all rats were tested for the performance of spatial learning and memory in Morris water maze. The number of newborn neurons in the DG was counted by using immunocytochemical method. The expression of the DCX protein and the level of DCX mRNA in the hippocampus of rats were measured by using Western blotting and RT-PCR technique, respectively. Results The results showed that: 1Compared with the ones of the control group, the multiple stressed rats had a significantly shorter latent period to search the platform in Morris water maze (P<0.05). 2 The number of newborn neurons in the DG of the multiple stressed rats was extremely higher than that of the control group (P<0.05). 3 The protein level of the doublecortin in the hippocampus of the multiple stressed rats were remarkably stronger than that of the control group(P<0.05). 4 The level of the doublecortin mRNA in the hippocampus of multiple stressed rats were markedly higher than that of the control group(P<0.05). Conclusion The newborn neurons in the dentate gyrus increased by the chronic multiple stress may participate in the course of enhancing the spatial learning and m