Objective : This study was examined to investigate the effect of Gamitongseong-san(GTS) extract on spontaneous hypertension. Methods : After administering GTS extract to SHR for 4 weeks, we measured anti-oxygen effects, weight of body, heart and kidney, blood pressure, heart rate, aldosterone, catecholamine, electrolyte, uric acid, and BUN. Results : 1. GTS increased 2,2-diphenyl-1-picrylhydrazyl(DPPH) scavenging activity and superoxide dismutase(SOD) similar activity depending on the concentration. 2. GTS significantly decreased heart weight in spontaneously hypertensive rat. 3. GTS significantly decreased blood pressure and heart rate in SHR. 4. GTS significantly decreased aldosterone. 5. GTS significantly decreased norepinephrine and epinephrine. 6. GTS significantly decreased $K^+$. 7. GTS significantly decreased BUN. Conclusions : These results suggest that GTS may be usefully applied for the treatment of hypertension.