Abstract:Two steroid saponins of yamogenin (A, C) had been isolated from the rhizome of Dioscorea collettii Hook. f. var. hypoglauca (Palibin) Pei et Ting. By means of acetylation, acid hydrolysis, enzymolysis, IR, MS and 13C-NMR the structure of saponin A named hypoglaueine A was proved as yamogcnin-3-O-[bis-α-L-rhamnosyl (1→2, 1→3)]-[β-D-glueopyranoside. Saponin C was identified as protohypoglaucine A.