A large number of association studies revealed the importance of gene polymorphisms in renin-angiotensin system(RAS) in the pathogenesis of hypertension. Among these many polymorphisms of RAS genes, M235T or G-6A polymorphism of angiotensinogen gene increases the risk for salt sensitivity, lacunar infarction, non-dipper type of blood pressure variation, etc. and plasma angiotensinogen level. On the other hand, homozygous deletion polymorphism of angiotensin converting enzyme gene(ACE DD) increases the risk for male hypertension, ischemic heart disease and renal disease via increase of plasma and tissue ACE levels, and shows poor response to medication. Gene targeting experiments in mice enable us to examine whether quantitative changes in gene expression in RAS affect blood pressure, resulted that a simple computer simulation concerning RAS and the kallikrein-kinin system(KKS) emphasize the importance of interaction between RAS and KKS. This mini-review also describes the effect of renin or AT1 receptor gene polymorphisms, and the role of RAS genes in the correlation between inflammation and atherosclerosis.