A new triterpenoid saponin, namely unifloroside, together with five known compounds, was isolated from Rhaponticum uniflorum (L.) DC. The structure of the new triterpenoid saponin was elucidated as 3_O_ α_L_arabinopyranosyl_urs_9(11),12_dien_28_oic acid β_D_glucopyranosyl ester mainly by using 1D, 2D_NMR techniques and chemical methods.
