The content of total flavonoids in an extract of Ginkgo biloba, called GBE50, is 44% by weight. This is significantly greater than that in a standard extract of Ginkgo biloba, designated EGB761. To date, the mechanisms by which GBE50 and EGB761 function remain poorly understood. In the present study, an experimental rat model of aging was induced by intraperitoneal injection of D-galactose, followed by intragastric perfusion of GBE50 (30, 60 mg/kg), or EGB761 (60 mg/kg). The water maze scores and hippocampal CA1 synaptic plasticity were evaluated. In the place navigation test, the GBE50 group rats did better than EGB761, while similar scores were obtained in the spatial probe test, and in the platform-switched test. In addition, long-term potentiation was significantly enhanced following high-frequency stimulation in the GBE50 and EGB761 groups, compared with the model group. These results demonstrate that GBE50 and EGB761 improved the leing and memory of aging rats. In particular, GBE50 administered at the 60 mg/kg dose exhibited superior effects over EGB761 at the same 60 mg/kg dose. Furthermore, the enhancement of hippocampal synaptic plasticity may be an underlying mechanism.