Curcuma xanthorrhiza Roxb. (Zingiberaceae) is a medicinal plant widely spread in South East Asia. In particular, it is commonly used not only for food and medicinal purposes in Indonesia, but also for the topical treatment of acne and skin inflammations as Thai traditional medicine. It was found that the methanol extract of C. xanthorrhiza inhibited significantly 7,12-dimethylbenz[a]anthracene (DMBA)-induced bacterial mutagenesis of Salmonella typhimurium TA98 and TA100 in the presence of S9, and the mutagenesis induced by H2O2 and tert-butylhydroperoxide in S. typhimurium TA102, respectively. In addition, 12-O-tetradecanolyphorbol-13-acetate(TPA)-induced mouse ear edema was markedly inhibited by pretreatment with C. xanthorrhiza extract. C. xanthorrhiza extract dose-dependently reduced ODC expression in mouse skin with TPA-induced acute inflammation. Furthermore, repeated treatment with 0.1% C. xanthorrhiza extract reduced the average number of tumors per mouse and the percentage of tumor-bearing mice in a multistage mouse skin carcinogenesis induced by DMBA and TPA. These results demonstrate that the methanol extract of C. xanthorrhiza possesses cancer chemopreventive potential.