Two new steroidal saponins (1 and 2) were isolated from the dried bulbs of Allium macrostemon Bunge. Their structures were elucidated by the spectral data as 26-O-beta-D-glucopyranosyl-5alpha-furost-25 (27)-ene-3beta, 12beta, 22, 26-tetraol-3-O-beta-D-glucopyranosyl (1-->2) [beta-D-glucopyranosyl (1-->3)]-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside (1) and 26-O-beta-D-glucopyranosyl-5beta-furost-20 (22)-25 (27)-dien-3beta, 12beta, 26-triol-3-O-beta-D-glucopyranosyl (1-->2)-beta-D-galactopyranoside (2), respectively. Their cytotoxic activities on several cancer cell lines (MCF-7, NCI-H460, SF-268 and HepG2) were tested. 1 showed special cytotoxity on SF-268, while 2 showed cytotoxity on NCI-H460 and SF-268 cell lines, respectively.