Abstract: The aim of the present study was to evaluate the inhibitory effect of Lactobacillus plantarum HI8 on genotoxicity induced by 4-NQO. The β-galactosidase and alkaline phosphatase producing feature of indicator strain E. coli PQ37 was identified by using SOS-chromotest, and the activity of [3-galactosidase in co-culture system of Lactobacillus plantarum H 18 and 4-NQO were determined. The results revealed that the expression of β-galactosidase and alkaline phosphatase was induced by a certain concentration of 4-NQO; when E. coli PQ37 was treated with 4-NQO over a range of concentrations （0-333.33 ng/mL）, the activity of alkaline phosphatase remained stable （ 11.95-14.40 U）, indicating that the selected concentration range of 4-NQO was proper for the successive test; the activity of β-galactosidase in co-culture system of LactobaciUus plantarum H18 and 3 concentrations of 4-NQO was decreased compare to the negative control; When Lactobacillus plantarum H18 co-cultured with 83.33 ng/mL 4-NQO, the highest inhibition rate （42.87%） was observed, indicating that Lactobacillus plantarum H18 was not a high-antinmtagenicity strain. In conclusion, Lactobacillus plantarum H18 shows inhibitory effect on genotoxicity induced by 4- NQO.