Objectives: This study was to assess the toxicity of Sipjeondaebo-tang by bacterial reverse mutation test. Methods: In this study, to evaluate the bacterial reverse mutation of Sipjeondaebo-tang water-extract, the in vitro Ames test using Salmonella typhimurium (TA98, TA100, TA1,535, TA1,537) and Escherichia coli(WP2uvrA) were performed with Sipjeondaebo-tang water extract at the concentrations 0, 312, 625, 1250, 2500 and 5000 ${mu}g/plate$. Results: Sipjeondaebo-tang water extract was negative in Ames test with both Salmonella typhimurium or Escherichia coli with and without rat liver microsomal enzyme (S9- fraction and S+ fraction). Conclusions: According to these results, we concluded that a Sipjeondaebo-tang water extract did not cause bacterial reverse mutation.