To investigate the effect of lycopene alone or in combination with vitamin E on BALB/c-3T3 cell transformation induced by benzo(a)pyrene. BALB/c-3T3 cells were plated at a density of 10,000 cells per plate in fourteen replicates/each treatment. After 24 hours,the test compounds(lycopene,lycopene and vitamin E,BaP) were added in medium,and the control cells received the vehicle and BaP,the cells were cultured for 3 days. Two plates from treated group were used for determination of the cytotoxicity,and other twelve plates were incubated in fresh DMEM/F12.The medium was changed twice a week,for 25 days of culture. Ten plates were fixed and foci in a diameter of more than 2 mm were counted;the remaining two plates were used for determination of p53 protein by sandwich ELISA. Tested chemicals lycopene and lycopene with vitamin E showed non-toxic or slightly toxic in cytotoxicity test. Transformation frequency induced by BaP was reduced by addition of 0.5 μmol/L,1 μmol/L,5 μmol/L lycopene,and the content of p53 protein in cells was very low. However,a higher dose of 10 μmol/L lycopene reduced this anti-transformed ability and p53 protein accumulated. Vitamin E enhanced the effect of lycopene on reduction of transformation frequency induced by BaP. The effective manner of lycopene of reduction in the transformation frequency induced by BaP is similar to its antioxidation. Lycopene has not been found the co-carcinogenic effect as β-carotene. Vitamin E may enhance the preventive effect of lycopene.