Abstract: Objective To explore the relationship between NQO 1 C609T gene polymorphism and the risk of colorectal cancer.Methods Ahospital-based case-controls tudy was conducted and polyme rase chain reaction-restriction fragment length polymorphism(PCR-RFLP)method was used to detect the genotypes.Results The frequency of C/T,T/T geno-type among cases with colorectal cancer were higher than those among the controls.As compared with the C/C genotypes,the NQO1 C/T,T/T geno type significan tlyinc reased the risk for developing colorectal cancer and the OR were 2.061(95%CI=1.372-3 097)and 2.640(95%CI=1.568-4.444),respectively 37.41% of C and 62.59% of T allele were distributed in colorectal cases while 50.17% of C and 49.83% of T in controls.In addition NQO 1 609 any T ganotype might in teract with smoking,drinking water and types of food to increase the risk of colorectal cancer.Conclusion NQO1 609 any T genotype might increase the risk of colorectal cancer development and the geno type might interact with othe renvironmental factors to increase the risk of colo rectal cancer.