Bacopa monnieri has been used in Ayurvedic medicine as a memory enhancer for a long time; however, its direct effect on synaptic plasticity has not been investigated. To the best of our knowledge, this study is the first to report the effect of B. monnieri on long-term synaptic potentiation in acute hippocampal slices. Adult male Wistar rats were orally administered either sterile water or the ethanolic extract of B. monnieri for 60 days. The extracellular recording was performed to measure the field excitatory postsynaptic potential in the acute hippocampal slices of these rats. Our results showed that B. monnieri extract significantly increased long-term potentiation magnitude compared with the control group, whereas there was no change in basal synaptic transmission. The data support the beneficial mnemonic effect of B. monnieri, and suggest that this effect might be because of the increase of learning-associated synaptic machinery, resulting in the long-term potentiation enhancement and strengthening of hippocampal synapses, which plays a critical role in learning and memory formation.