A new dammarane-glycoside, ginsenoside Rz(1) (1), was isolated from heat-treated Panax ginseng C. A. MEYER (Araliaceae) with ginsenosides Rk(1) and Rg(5). The structure of 1 was established to be (Z)-12 beta-hydroxydammara-20(22),24-dien-3 beta-yl O-beta-D-glucopyranosyl-(1 -> 2)-beta-D-glucospyranoside by spectroscopic means. HPLC analyses revealed that the ginsenosides Rz(1) Rk(1) and Rg(5) were present in the ratios of 1 :2: 6, respectively.