Abstract: ObjectiveTo assess the association between T-786C mutation in endothelial nitric oxide sy nthase gene and premature coronary heart disease(p-CHD).Methods188 new CHDpatients diagnosed at/before aged 55 for males and 65 for females were assigned to p-CHD case group with other 315 CHD patients as the control group.Polymerase chain reaction with MspI restriction enzyme digestion was performed to detect the T-786C mutation.Univariate test and stepwise multiple Logistic reg ression models were used to ananlyze the association between T-786C mutation and p-CHD.ResultsThere was no significant difference in T-786C mutant genotypes between p-CHD group and control group(P=0.105).However,mutant genotypes(TC+CC)in p-CHD group were significantly higher than those in control group(P=0.039).Mutant Callele frequency in p-CHD group was also significantly higher than that in control group(14.63% versus 10.32%, P=0.041,OR=1.489,95% CI:1.014-2.187).Stepwise multiple Logistic regression analysis at 0.05 significant level with sex,smoking,alcohol drinking,and overweight covariates indicated that T-786C mutation still had significant effect on p-CHD(P=0.013,OR=1.791,95% CI:1.131-2.897).ConclusionT-786C mutation in endothelial nitric oxide synthase gene mig ht serve as a major risk factor of p-CHD.