Papillomas in mouse skin were initiated with 390 nmol of 7,12-dimethylbenz(a)anthracene and 1 week later, were promoted 2 times a week with 4.1 nmol of 12-O-tetradecanoylphorbol-13-acetate (TPA). Five saponin-related compounds used as potential anti-inflammatory agents were applied in the same position with 82 nmol. Saponin-related compounds effectively inhibited tumor formation in the sensitive mouse stock even when these compounds were given 1 h prior to TPA treatment. These results suggested that there was a general correlation between the anti-inflammatory and antitumor-promoting activities of saponins.