The present work was done to isolate the anthelmintic substance from the tuber of Bletilla striata which grows Gangweon-do of the Korea peninsula. The dried B. striata tuber was extracted with ethyl ether by a Soxhlet extractor at 40C for 24 hours, and then the extract was separated into insoluble material (negative wormicidal) and soluble material (positive wormicidal) by petroleum ether solvent. The wormicidal substance was separated in the silica gel column chromatography from the petroleum ether extract, using benzene (90 percent) and acetone (10 percent) as a solvent. The anthelmintic activity was observed in vitro on the cercaria, the excysted metacercaria and the adult of Clonorchis sinensis. On the silica gel thin layer chromatography with the wormicidal substance in benzene:acetone/90:10, five spots were observed in iodine chamber and the spot of Rf. 0.18 value of them appeared the most strong wormicidal effect on the cercaria of C. sinensis. Afterward, a substance which was equivalent to the Rf. 0.18 value spot was isolated from the wormicidal substance by means of silica gel column chromatography using 1 part of ethyl acetate and 6 parts of chloroform carrier, and the excysted matacercaria and the adult of C. sinensis were killed within 14 minutes and 128 minutes in the substance.
