The ability of lettuce and chard extracts to reduce the mutagenic activity of Benzo[a]pyrene was studied. In this experiment several groups of male Balb/C mice were treated with different doses of the substances under study. B[a]p was administered at doses of 36 and 72 mg/kg of body weight to groups II and III, respectively. The lettuce extract combined with the doses of B[a]p were administered to groups IV and V. The experiment was performed again under the same conditions to test the effect of chard extract. Urine samples were tested by means of the Ames assay. The results show that the mutagenic activity of the urine samples from groups treated with B[a]p was reduced when the treatment also included any vegetable extract.