Three new pregnane glycosides, named periplocosides A, B and C, have been isolated from the antitumor fraction, which was obtained by subjecting the CHCl3 extract of Periploca sepium to column chromatography over silica gel and eluting with CHCl3-MeOh (10 : 1). Their structures were established by various nuclear magnetic resonance techniques and chemical evidence. The major constituents, periplocoside A, showed significant antitumor activity against Sarcoma 180 ascites in mice.