Antimutagenic effect of Eleutherococcus senticosus Maxim. on the mutagenicity induced by 2-AF and Trp-P-1 was studied using the Ames test with Salmonella typhimurium TA98 and TA100. In S. typhimurium TA98, the methanol extract of root, stem, and leaf of E. senticosus showed inhibitory effects of 72.8, 70.0, and 78.7% on the mutagenicity induced by 2-AF, and 69.2, 64.9, and 59.4% by Trp-P-1, respectively, whereas none was observed in S. typhimurium TA100. These results suggest that the methanol extract of E. senticosus inhibits a frame shift mutation. And then the methanol extract further fractionated by chloroform, butanol, and water. The chloroform fractions of root, stem, and leaf showed strong antimutagenic effects induced by 2-AF and Trp-P-1 in S. typhimurium TA98, whereas none was observed in the butanol and aqueous fractions. The chloroform fractions of root, stem, and leaf showed antimutagenic effects of in a dose-dependent manner.