To access the safety and efficacy of Chungyeoldodam-tang(CDT), a traditional herbal medicine prescription, on hypertension we examined various parameters involved in the pathogenesis of hypertension. CDT seems to be safe because CDT at the concentrations lower that 250 ug/ml showed no toxic effects in cultured human fibroblast and no toxic effects on liver function. The production of reactive oxygen species (ROS) were greatly decreased in CDT treated group compared with control, and angiotensin converting enzyme activities were reduced by CDT in a dose dependent manner. There was no differences in weight of hearts between control and CDT treated group. The blood pressure and pulse rate were significantly decreased. CDT greatly reduced the levels of plasma hormones including aldosterone, dopamine, and norepinephrine, but not epinephrine, and serum electrocytes including Na$^+$ and Cl$^-$, but not K$^+$. were also decreased. The levels of uric acid, BUN and creatinine were significantly decreased compared with control. These results suggested that CDT has suppressive effects on various pathologic factors in hypertension, and CDT has potential as a safe and effective therapeutics for hypertension.