Blood pressure, obesity and bone mineral density are multifactorial traits influenced by genetic factor. The purpose of this study was to clarify the association between three genetic polymorphisms in the estrogen receptor-$alpha$ (ER -$alpha$) gene and essential hypertension in korean population. One hundred and seventy-one people including 90 normotensives and 81 essential hypertentives were recruited. Among genetic polymorphisms studied, the Xba I RFLP in the intron 1 of this gene polymorphism was significantly associated with essential hypertension in women, suggesting the sexual dimorphism in genetic effect (P (<) 0.05). Further studied suggest that a larger sample size of this study are needed.