A new polyhydroxylated cholestane trisdesmoside and a new spirostanol pentasaccharide, together with five known spirostanol saponins, were isolated from the bulbs of Allium macleanii, and two known spirostanol saponins were isolated from the bulbs of A. senescens. The identification and structural assignments of the steroidal glycosides were performed by spectroscopic analysis and hydrolysis. Furthermore, the isolated compounds were evaluated for inhibitory activity on 12-O-tetradecanoylphorbol-13-acetate (TPA)-stimulated 32P-incorporation into phospholipids of HeLa cells, which is recognized as an excellent primary screening test to identify new antitumour-promoter compounds.