This study investigated the inhibitory effects of aqueous extracts from Miracle Fruit leaves (AML) on mutation and oxidative damage. The results showed that AML in the range of 1-5 mg/plate inhibited the mutagenicity of 2-aminoanthracene (2-AA), an indirect mutagen, and 4-nitroquinoline-N-oxide (4-NQO), a direct mutagen toward Salmonella typhimurium TA 98 and TA 100. On the other hand, AML in the range of 0.05-0.2 mg/ml showed radical scavenging, reducing activities, liposome protection as well as decreased tert-butyl hydroperoxide (t-BHP) induced oxidative cytotoxicity in HepG2 cells. High performance liquid chromatography (HPLC) analysis suggested that the active phenolic constituents in AML are p-hydroxybenzoic acid, vanillic acid, syringic acid, trans-p-coumaric acid and veratric acid. These active phenolic components may contribute to the biological protection effects of AML in different models. The data suggest that AML exhibiting biological activities can be applied to antimutation as well as anti-oxidative dama