BR003 is a multi-herbal formula that contains twelve medicinal herbs. We investigated the effects of oral administration of BR003 to Wistar rats on (a) learning and memory using a passive avoidance test and (b) cell proliferation in the dentate gyrus (DG) of the hippocampus using immunohistochemical analysis of 5-bromo-2-deoxyuridine (BrdU) expression. In the passive avoidance test, the retention time of the BR003-treated group was significantly longer than that of the control group (182.64+/-39.88 vs. 73.08+/-29.30 s, respectively; n=11; p<0.05). There were significantly more BrdU-immunoreactive cells in the DG in the BR003-treated group than in the control group (1281.07+/-151.16 vs. 818.01+/-132.98 cells per DG, respectively; n=11; p<0.05). These results suggest that the administration of BR003 not only improves learning and memory but also increases cell proliferation in the DG of the rat hippocampus.