Much attention is recently gained for Elsholtzia splendens extracts and issue on their usage is raised due to their biological properties. However, there is no sufficient background information on toxicological evaluation of E. splendens extracts to give an assurance of safety for developing dietary supplements and functional foods. The objective of this study was to evaluate safety on E. splendens extracts using acute oral toxicity, bacterial reverse mutation, and chromosome aberration test. Total flavonoids within E. splendens were extracted with 80% of methanol by a reflux condenser. Both female and male mice were orally administrated E. splendens extracts at the dose of 0, 500, 1000, and 2000 mg/kg body weight/day. Mutagenicity of the extracts was evaluated in a bacterial reverse mutation assay using histidine requiring Salmonella typhimurium (TA 98, TA 100, TA 1535, and TA 1537) and tryptophan-requiring Escherichia coli (WP2uvrA). In vitro chromosome aberration assay in Chinese Hamster Lung (CHL) was conducted to evaluate genotoxicity. Single administration of dose levels of 500, 1000, and 2000 mg/kg body weight/day to mice for 15 days did not produce any significant mortality, clinical signs, body weight loss, and gross findings. E. splendens extracts in the range of 156.3-5000 microg/plate did not induce mutagenicity in S. typhimurium and E. coli with and without metabolic activation system. Any significant chromosomal aberration was not observed in CHL cells 6h after treating with the extract at the concentrations of 1250, 2500, and 5000 microg/mL in absence and presence of metabolic activation system. However, frequency of chromosomal aberration in 22 h after treatment without metabolic activation system was increased with showing a pattern of dose-response relationship. The highest concentration of 5000 microg/mL significantly induced chromosomal aberration. E. splendens extracts may induce chromosomal structure abnormality in CHL cells. This study suggests that further study is needed to assess the potential genotoxic effects of E. splendens extracts.