Ethnopharmacological Relevance: The rhizomes of Dioscorea membranacea Pierre (DM) have been used as ingredients in anticancer herbal formulations in Thai traditional medicine (TTM). Thus, the aim of this study was to investigate the active constituents of DM for cytotoxic activity in order to support its TTM use.Materials And Methods: A bioassay-guided isolation procedure was used to separate the cytotoxic constituents from ethanolic extract of Dioscorea membranacea rhizomes by testing against five human cancer cell lines, i.