Background Cytochrome P450 2E1(CYP2E1)has an important role in the metabolic activation of precarcinogenssuch as N-nitrosoamines and other low relative molecular mass,organic compounds.This study examined whetherCYP2E1 Rsal and Dral polymorphism are associated with susceptibility to esophageal squamous cell carcinoma and thecorrelation between the genotypes and expression levels of CYP2E1 mRNA.Methods Seventy-seven patients with newly diagnosed,untreated esophageal squamous cell carcinoma and 79healthy controls matched in age,gender and residence were recruited for the control study.An Rsal polymorphism in the5’-flanking region and a Dral polymorphism in the sixth intron of the CYP2E1 gene,which could possibly affect itstranscription,were determined in this study by polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP)and mRNA level of CYP2E1 was measured by quantitative real-time reverse transcription PCR.Results No significant association of Rsal or Dral polymorphism of CYP2E1 with susceptibility of esophagealsquamous cell carcinoma were demonstrated(OR=1.67,95%Cl:0.89-3.15,P=0.11;OR=1.11,95%Cl:0.59-2.09,P=0.74,respectively).With SHEsis software,no linkage disequilibrium was detected between Rsal and DralpolymorphJsm(D’=0.528,r~2=0.27).When combined Rsal polymorphism with Dral polymorphism,the associationbetween that carrying c~2 allele and DD genotype and the risk for esophageal squamous cell carcinoma were found(0R=5.77,95%Cl:1.65-20.22).Compared with the normal controls,the mRNA levels with Rsal polymorphism,Dralpolymorphism,or any combined genotypes in cases showed no statistical difference.Conclusions This study suggests that carrying c~2 allele and DD genotype conferreded an elevated risk for esophagealsquamous cell carcinoma.There was no significant statistical relationship between the genotypes c1/c2,D/C,or thecombined allele and mRNA expression. Background Cytochrome P450 2E1 (CYP2E1) has an important role in the metabolic activation of precarcinogenssuch as N-nitrosoamines and other low relative molecular mass, organic compounds. This study examined whether CYP2E1 Rsal and Dral polymorphism are associated with susceptibility to esophageal squamous cell carcinoma and thecorrelation Between the genotypes and expression levels of CYP2E1 mRNA. Methods Seventy-seven patients with newly diagnosed, untreated esophageal squamous cell carcinoma and 79 healthy controls matched in age, gender and residence were recruited for the control study. Ann Rsal polymorphism in the 5’-flanking region and a Dral polymorphism in the sixth intron of the CYP2E1 gene, which could possibly affect itstranscription, were determined in this study by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and mRNA level of CYP2E1 was measured by quantitative real-time reverse transcription PCR. Results no significant association of Rsal or Dral polymo rphism of CYP2E1 with susceptibility of esophageal squamous cell carcinoma were demonstrated. With SHEsis software (OR = 1.67, 95% Cl: 0.89-3.15, P = 0.11; OR = 1.11, 95% Cl: 0.59-2.09, , no linkage disequilibrium was detected between Rsal and DralpolymorphJsm (D ’= 0.528, r ~ 2 = 0.27) .When combined Rsal polymorphism with Dral polymorphism, the associationbetween that carrying c ~ 2 allele and DD genotype and the risk for esophageal squamous cell carcinoma Compared with the normal controls, the mRNA levels with Rsal polymorphism, Dralpolymorphism, or any combined genotypes in cases showed no statistical difference. Conclusions This study suggests that carrying c ~ 2 allele and DD genotype conferreded an elevated risk for esophageal squamous cell carcinoma. There was no significant statistical relationship between the genotypes c1 / c2, D / C, or the combined allele and mRNA expression.