OBJECTIVE: Bacopa monniera (BM), a traditional Ayurvedic medicine has been used in treatment for a number of disorders, particularly those involving anxiety, intellect and poor memory. The current study examined the effects of standardized extract of Bacopa monniera on the dendritic morphology in adult rats of hippocampal CA3 neurons, one of the regions concerned with learning and memory. MATERIALS AND METHODS: Adult Wistar (2.5-month-old) rats were designated into 2-, 4- and 6-week treatment groups. Rats in each of these groups were divided into 20 mg/kg, 40 mg/kg and 80 mg/kg dose groups (n=8 for each dose). These rats along with age-matched control rats were then subjected to spatial learning (T-maze) and passive avoidance tests. Subsequent to the T-maze and passive avoidance tests, these rats were killed by decapitation, brains were removed and hippocampal neurons were impregnated with silver nitrate (Golgi staining). Hippocampal CA3 neurons were traced using camera lucida. Dendritic branching points (a measure of dendritic arborization) and dendritic intersections (a measure of dendritic length) were quantified. These data were compared with control rats. RESULTS AND CONCLUSIONS: The results showed improvement in spatial learning performance and enhanced memory retention in rats treated with BM extract. There was a significant increase in the dendritic intersections and dendritic branching points along the length of both apical and basal dendrites in rats treated with BM extract for four and six weeks. However, the rats treated with BM extract for two weeks did not show any significant change in hippocampal CA3 neuronal dendritic arborization. We conclude that constituents present in BM extract have neuronal dendritic growth stimulating properties.