Complex quantitative traits such as blood pressure are influenced by genetic and environmental factors. Candidate genes that blood pressure variation includes renin-angiotensin system, kallikrein kinin system, natriuretic peptide system, and so on. Thus, we perfomed case-control studies using genetic markers in Korean normotensives and hypertensives, respectively. Allele frequencies were not significantly different between the two groups(P>0.05). We also performed SSCP analysis for renin gene. Abnormal band did not detected. But, The allele frequency of ScaI RFLP at the atrial natriuretic peptide (ANP) gene in Koreans (0.12) was similar to those of Mauritian Indians (0.10). Thus, ScaI RFLP at the ANP may be useful as the genetic marker to study on the ethnic or racial groups.