Abstract: ObjectiveTo assess the association between intron 4 VNTR polymorphism in endothelial nitric oxide synthase(eNOS)gene and premature coronary heart disease(p-CHD).MethodAhospital-based case-control study was conducted.Newly-diagnosed CHD patients were recruited as this study subjects.one hurdthd and eighty-eight CHD patients diag nosed at/before 55 years old for males and 65 for females were assigned to p-CHD case group with other 315 CHD patients as the control group.Genotypes were detected by polymorphism chain thaction(PCR)technique.ResultsThe genotype fthquencies of c/c,c/b,b/b,b/a,a/a were 0.53%,0.00%,81.38%,16.49%,1.60% in p-CHD group thspectively and 0.00%,0.32%,77.46%,20.32%,1.90% in the control group respectively.There was no significant difference betw een the p-CHD and the control group for comparing genotype frequencies of c/c+c/b+b/b with b/a+a/a(P=0.268, OR=11294,95% CI=0.820~2.043).The allele frequencies of c,b,a were 0.53%,89.63%,9.84% in the p-CHD group respectively and 0.16%,87.78%,12.06% in the control group respectively.There was also no significant difference between the p-CHDand the control group for comparing allele frequencies of c+b with a(P=0.280,OR=1.257,95% CI=0.830~1.904).Stepwise multiple logistic thgression analysis at 0.05 significant level with adjust ment of sex,smoking,alcohol drinking,systolic blood pressure,over weight,waist-hipratio,serum trigly ceride,serum total cholesterol covariates showed that the eNOS4a had no significant effect on p-CHD(P=0.427,OR=0.819,95% CI=0.500~1.341).ConclusioneNOSintron 4 a/b VNTR polymorphism is not a risk factor for p-CHD.