BACKGROUND Forsythia viridissima fruit, one of Forsythiae Fructus (FF) is widely used in traditional medicine to treat diverse diseases-related clinical symptoms, including fever, pain, vomiting, nausea, and abscess. However, the safety of FF has not been fully assessed. OBJECTIVE In this study, we evaluated the acute oral toxicity and genotoxic potential of an aqueous extract of Forsythia viridissima fruits (EFVF). METHODS For an acute oral toxicity test, male and female SD rats (n = 5) orally received a single dose of 5000 mg/kg EFVF. The genotoxic potential of EFVF was evaluated with a battery of tests, including an in vitro bacterial reverse mutation test using five mutant strains of Salmonella typhimurium (TA100, TA1535, TA98, TA1537) and Escherichia coli (WP2 uvrA), an in vitro chromosomal aberration test using Chinese hamster lung (CHL/IU) cells, and an in vivo micronucleus test using bone marrow cells in male ICR mice that were orally administered EFVF. All tests were completed in compliance with Organization for Economic Cooperation and Development guidelines and/or regional regulatory standards for toxicity tests. RESULTS In the acute oral toxicity test, the animals did not show any significant mortality and body weight changes for 14 days following a single dose of EFVF at 5000 mg/kg. There was no evidence of genotoxicity of EFVF based on the results of the in vitro bacterial reverse mutation test (up to 5000 μg/plate), the in vivo micronucleus test (up to 5000 mg/kg), and the in vitro chromosomal aberration test (1100-2500 μg/mL). CONCLUSIONS We found that EFVF is safe with regard to acute toxicity in rats as well as genotoxicity such as mutagenesis or clastogenesis under the present experimental conditions. These results might support the safety of EFVF as a potential therapeutic material for the traditional use or pharmaceutical development.