Butea superba is a traditional tuberous Thai plant enriched with flavonoids that is used for treating erectile dysfunction. We investigated the mutagenic and antimutagenic potentials of a B. superba extract by using the pre-incubation method of the Ames test. Salmonella typhimurium strains TA 98 and TA 100 were applied as the tester strains in the presence and absence of an S9 mixture. Prior to the mutagenic and antimutagenic tests, the survival of the tester strains was measured by treating with the B. superba extract. The results show that the B. superba extract exhibited dose-dependent cytotoxic effects. Data from the Ames test revealed that the B. superba extract to be non-mutagenic in the presence and absence of the S9 mixture. In contrast, the B. superba extract showed antimutagenic potential towards either or both of the tested mutagens: 2-(2-furyl)-3-(5-nitro-2-furyl)-acrylamide (AF-2) and benzo(a)pyrene (B(a)P) in the respective presence and absence of the S9 mixture, respectively. The plant antimutagenic activity was confirmed by a rec assay. A further study by micronucleus test demonstrated that the B. superba extract at the maximum loading volume could induce acute micronucleus formation in the tested animals. The in vitro mutagenic and antimutagenic assays confirmed the safe consumption of B. superba products at low dose (not more than 781.25 microg/ml of the plant extract), but the in vivo genotoxic assay demonstrated the unsafe consumption at a high dose (300 mg/kg of the BW plant extract or 16 g/kg of the BW plant powder).