Two new triterpenoid saponins, named platycodon A (3-O-β-D-glucopyranosyl-16-O-β-D-glucopyranosyl-2β,3β,16β,21β-tetrahydroxyolean-12-en-28-oic acid) and platycodon B (3-O-β-D-glucopyranosyl-16-O-β-D-xylopyranosyl-2β,3β,16β,21β-tetrahydroxyolean-12-en-28-oic acid) were isolated from the roots of Platycodon grandiflorum. The structures of these compounds were elucidated by means of various spectroscopic analyses. Compounds 1 and 2 were tested in HepG-2, A549 and DU145 human cancer cell lines and showed remarkable cytotoxic activities against HepG-2 and A549 cancer cell lines with IC(50) values ranging from 4.9 to 9.4 µM, but they displayed weak cytotoxic activities against DU145 cancer cell line with IC(50) values greater than 10 µM.