A new spirostanol saponin was isolated from the underground parts of Ruscus aculeatus and the structure was assigned as (23S,25R)-spirost-5-ene-3β,23-diol 23-O-{O-β-d-glucopyranosyl-(1->6)-β-d-glucopyranoside} on the basis of spectroscopic analysis, including two-dimensional NMR spectroscopic techniques and the result of acid hydrolysis. The saponin is unique in structure having a diglycoside unit at C-23 of the spirostanol skeleton.