Objective To study the triterpene saponins from Gynostemma pentaphyllum with antitumor activities.Methods The 75% EtOH extract of G.pentaphyllum was used for isolation by silica gel column chromatography and preparative HPLC.The structures of pure compounds isolated were identified by the spectral analysis and chemical evidence.Results Two compounds were isolated and identified as 23(S)-3β,20ξ,21ξ-trihydroxy-19-oxo-21,23-epoxydammar-24-ene 3-O-α-L-rhanmopyranosyl(1→2)-[β-D-xylopyranosyl(1→β)]-β-D-arabinopyranoside(1)and23(S)-21(R)-O-n-butyl-3β,20ξ-dihydroxy-21,23-epoxydammar-24-ene 3-O-α-L-rhamnopyranosyl(1→2)-[β-D-xylo-pyranosyl(1→3)]-β-D-arabinopyrannside(2).Conclusion Compound 2 is a new triterpene saponin with moderate antitumor activities against the HL-60,Colon205,and Du145 cell lines.