The roots of Liriope platyphylla (Liliaceae) are widely used in traditional Chinese medicine. In the present study, we investigated the effects of ethanol (70%) extract of the roots of Liriope platyphylla (ELP70) on learning and memory using behavioral and immunohistochemical methods in mice. Control animals were treated with vehicle (10% Tween 80). With sub-chronic treatments of ELP70 (p.o.) for 14 days, the latency time was significantly increased compared with that of the vehicle-treated control group (50, 100 and 200 mg/kg; P<0.05). Moreover, immunopositive cells for brain derived neurotrophic factor (BDNF) were significantly increased in the hippocapmpal dentate gyrus and CA1 regions after ELP70 treatments for 14 days (50, 100 and 200 mg/kg; P < 0.05). In addition, those cells for nerve growth factor (NGF) were also increased in the hippocapmpal dentate gyrus region (50, 100 and 200 mg/kg; P<0.05). These results suggest that the sub-chronic administration of ELP70 improves learning and memory, and that their beneficial effects are mediated, in part, by the enhancement of BDNF or NGF expression.