Salvia miltiorrhiza is a traditional Chinese medicine which has been well documented for its anti-cancer effects. Based on the structure of danshinone, one of the active compounds derived from Salvia miltiorrhiza, we synthesized a simplified phenolic analog, S-3-1, and tried to explore its possible actions in preventing the development of cancer. With the Ames test, S-3-1 was found to efficiently suppress the mutagenicity of benzo[a]pyrene. This result is consistent with the inhibitory effect of S-3-1 on the activation of benzo[α]pyrene by hepatic microsomal enzymes. Besides the anti-initiation effects, S-3-1 could significantly inhibit the croton oil induced increase of mouse skin epithermal oithine decarboxylase activity. Moreover, S-3-1 quenched both superoxide and hydroxyl free radicals whereas it inhibited lipid peroxidation in the in vitro model. These results suggest that S-3-1 might act as anti-initiation and anti-promo tion agents through reversing the biochemical alterations induced by carcinogen during carcino genesis. Therefore, we further investigated the effects of S-3-1 on carcinogenesis. In vitro, S-3-1inhibited the benzo[a]pyrene-induced transformation of V79 Chinese hamster lung fibroblasts.At 10-40 mg/kg, S-3-1 was found to inhibit the development of DM BA/croton oil-induced skin papilloma in mice through decreasing the incidence of papilloma, prolonging the latent period of tumor occurrence and reducing tumor number per mouse in a dose-dependent manner. We concluded from this study that S-3-1 might be developed as a new chemopreventive drug.