The effect of two different doses (400 and 800 mg/kg body wt/day for 15 days) of a 95% ethanolic extract of the seeds of Brassica compestris (var sarason) was examined on carcinogen metabolizing phase-I and phase-II enzymes,antioxidant enzymes and glutathione content and lipid peroxidation in the liver of Swiss albino mice. Positive control mice were treated with butylated hydroxyanisole (BHA). Significant elevation in the levels of cytochrome p450 (p<0,.05), cytochrome b5 (p < 0.05) glutathione s-transferase (p<0.01), DT-diaphorase (p<0.05), superoxide dismutase (p<0.01), catalase (p < 0.001) and reduced glutathione (p<0.001) was noted in the group treated with 800 mg/kg body wt. of Brassica extract in comparison with the negative control group. Brassica compestris acted as a bifunctional inducer since it induced both phase - I and phase - H enzyme systems. Since phase-I and phase-II enzymes are considered to be reliable markers for evaluating the chemoprevention efficacy of particular test materials,these findings are suggestive of potential chemopreventive roles for Brassica seed extract.