Objectives : This study was done to investigate the effect of Gamigehyuldeung-tang on hypertension. Methods : After administering Gamigehyuldeung-tang extract to SHR(Spontaneous Hypertensive Rats) for 5 weeks, changes in blood pressure, pulse rate, aldosterone and catecholamine levels in plasma were examined, and immunohistochemical changes and scanning electron microscopic changes were observed. Results : The following results were obtained; blood presure decreased significantly as well as levels of aldosterone, dopamine and epinephrine in SHR. But levels of norepinephrine were unaffected. No capillary vessel dilation was observed. A decrease in cell damage was seen in microscope investigation. Conclusions : These results support a role for Gamigehyuldeung-tang might be usefully applied in treatment of hypertension.