From leaves and stem-bark of Korean medicinal plant, Acanthopanax chiisanensis, a new glycoside was isolated and its structure was established as the α-L-rhamnopyranosyl (1→4)-β-D-glucopyranosyl (1→6)-β-D-glucopyranosyl ester of 1 (R)-hydroxy-3, 4-seco-lup-4 (23), 20 (30)-dien-3, 11α-olactone. This is the first example of a naturally occurring glycoside of 3, 4-seco-triterpene.