On hydrolysis with dilute mineral acid, ginseng saponins, ginsenosides-Rb1, -Rb2, -Rb3, -Rc, and Rd yielded panaxadiol (IV), and ginsenosides-Re, -Rf, -Rg1, and Rg2 and 20-glucoginsenoside-Rf afforded panaxatriol (X). The optimal condition of saponin hydrolysis for the quantitative analysis of IV and X was studied. The crude hydrolysates of methanol extract of ginseng were trimethylsilylated with N-trimethylsilylimidazole and the saponin content was calibrated by the gas chromatographic determination of TMS-panaxadiol and TMS-panaxatriol, using diacetylhederagenin methyl ester as the internal standard. This procedure was applied to the evaluation of the commercial ginseng tea and ginseng extract.