To examine the neuroprotective effects of Glycine max, we tested its protection against the glutamate-induced toxicity in primary cortical cultured neurons. In order to clarify the neuroprotective mechanism(s) of this observed effect, isolation was performed to seek and identify active fractions and components. From such fractionation, two triterpene glycosides, 3-O-[alpha-L-rhamnopyranosyl(1-2)-beta-D-glucopyranosyl(1-2)-beta-D-glucuronopyranosyl]olean-12-en-3 beta,22 beta,24-triol (1) and 3-O-[beta-D-glucopyranosyl(1-2)-beta-D-galactopyranosyl(1-2)-beta-D-glucuronopyranosyl]olean-12-en-3 beta,22 beta,24-triol (2) were isolated with the methanol extracts with of air-dried Glycine max. Among these compounds, compound 2 exhibited significant neuroprotective activities against glutamate-induced toxicity, exhibiting cell viability of about 50% at concentrations ranging from 0.1 mu M to 10 mu M. Therefore, the neuroprotective effect of Glycine max might be due to the inhibition of glutamate-induced toxicity by triterpene glycosides.