Materials and Methods: Total 24 male rats divided into four groups were used (n=6) for this study. Group I was control in which rats were kept under ideal laboratory conditions, Group II was given 40 mg/kg of BM extract, Group III was cold water swim stress in which rats were forced to swim in the cold water maintained at 18±2°C till it started to sink for a period of one month and Group IV in which cold water swim stress given for a month followed by oral administration of BM extracts 40mg/ kg treatment for a month. The whole study was carried out for a period of 60 d. The animals were sacrificed next day and their brains dissected out for histomorphometric analysis. The diameter, packing density and total number of neurons were calculated from stained histological section by using micrometry in the CA-1 region of the hippocampus. Statistical Analysis: The analysis and plotting of graphs were carried out using Sigma Plot 12 (Systat Software Inc., USA). Values are expressed as Mean ± SEM (n = 6). One way analysis of variance followed by Student-Newman-Keul’s multiple comparisons test was used for the comparison of means. A probability of 0.05 and less was taken as statistically significant. Results: The results showed that there is no significant difference in the diameter of the cells between the groups but total number of the cells in Group II was statistically significant when compared with the others groups. Student–Newman– Keuls method showed that Group II and Group IV are statistically significant when compared to Group III (p<0.05). Conclusion: Results indicates that when BM extracts administered orally produce neuroprotective effect in cold stress induced hippocampal neurodegeneration of rats. Hence, the herb BM can possibly be used as an adjuvant to improve memory to combat stress in our day to day life. Introduction: Bacopa monniera/ Brahmi,is used over centuries in Ayurvedic medicine for memory development, learning, concentration and other mental illnesses such as nervousness and poor cognition. The present study aims to evaluate the effect of Bacopa monniera (Brahmi, BM) on cold stress induced histological changes in hippocampus of Wistar rats. © 2015, Journal of Clinical and Diagnostic Research. All rights reserved.