Bioassay-guided fractionation of an H2O extract of the root of Scutellaria baicalensis has furnished an in vitro antigenotoxic flavonoid, baicalein (1) and 2’,5,5’,7-tetrahydroxy- 6’,8-dimethoxyflavone (2). Compound 1 exhibited a dose-dependent inhibition of aflatoxin B1 (AFB1) and N-methyl-N’-nitro-N- nitrosoguanidine mutagenicity in the Salmonella typhimurium bacterial mutation assay. In the chromosome aberration assay, compound 1, at a concentration of 5µM, reduced the frequency of chromosome aberration induced by AFB1 but increased the clastogenic effect of AFB1 at a concentration of 50µM.