Abstract: Objective To explore the impact of interaction between renin gene insertion/deletion(REN gene I/D)polymorphism and environmental factors on essential hypertension(EH)in Mongolian people,China.Methods 501 Mongolian people(243 hypertensives and 258 normotensives)who had no blood relationship with each other,were selected as subjects to conduct the case-control study.All the subjects were interviewed with questionnaire and their blood specimens were collected.Renin gene I/D polymorphism was genotyped with polymerase chain reaction(PCR),polyacrylamide gel electrophoresis and silver staining.Results The frequencies of renin gene genotypes DD,alleles D in the hypertensive subjects(36.21%,63.79%)were significantly higher than those in the normotensive subjects(29.84%,57.17%)(P<0.05).The OR of renin gene genotype(DD+ID)and cigarette smokers to renin gene genotype Ⅱ and non-smokers on EH was 1.70(95% CI 0.69～4.48).There was a positive interaction between renin gene and cigarette smoking on EH accorcling to analysis of multiplicative model.The OR of renin gene genotype(DD+ID)and alcohol drinkers to renin gene genotype Ⅱ and non-drinkers on EH was 3120(95%CI1.42～7.61).There was a negative interaction according to analysis of multiplicative model between renin gene and alcohol intake on EH.Conclusion Cigarette smoking or alcohol intake can increase the risk on EH when people have an genotype ID or DD of renin gene.