Bioassay-guided fractionation of a MeOH extract of the rhizomes of Astilbe koreana (Saxifragaceae), using an in vitro protein tyrosine phosphatase 1B (PTP1B) inhibitory assay, resulted in the isolation of a new triterpene, 3alpha,24-dihydroxyolean-12-en-27-oic acid (4), along with four triterpenes,