Water extracts of leaves of black tea, oolong tea, and green tea, were examined for antimutagenic activity with Salmonella typhimurium test strains, TA 98 and TA 100. These water extracts significantly decreased the reverse mutation induced by crude dimethyl sulfoxide extracts of grilled beef and, by Trp-P-1, Glu-P-1, and B[a]P in the presence of a rat liver microsomal activation system. They also decreased the mutagenicity of AF-2 and 4-NQO requiring no metabolic activation to cause the mutation. Removal of caffeine from tea extracts did not influence the DEGB-induced mutation, but ethyl acetate extraction abolished the effect.