Genetic polymorphisms of the renin-angiotensin system (RAS) have been associated with hypertension in various ethnic groups, but no relation between these polymorphisms and hypertension has yet been systematically evaluated. To assess the relationship between allelic variation of RAS genes and hypertension, we performed the case-control studies using genetic markers in Korean normotensives and hypertensives. The allele and genotype frequencies of RAS genes in Korean population were not significantly different between normotensives and hypertensives. To investigate the distribution of allele frequencies among various populations, the data obtained in this study were compared to those in other ethnic groups studied previously. Except for T174M polymorphism of angiotensinogen (AGT) gene, allele frequencies of RAS genes were different among racial groups. The reason for these differences may be due to the difference in various genetic or environmental background or due to the effects by various sample size studied. In addition, it can be emphasized that carefully designed studies are required to minimize the ethnic heterogeneity of the case and control populations.