Afterwards, the experimental animals were given the extract of rosela liquid with the dose 1 mg, 5 mg, 25 mg, and 125 mg/ kg body weight. It resulted that the blood presure of the mice which were given with 125 mg/kg dose of rosela extract was decreased to 2,5 times compared to the control group. The mechanism of anti-hypertension effect of rosela petals is traced by isolating the aorta ring of mice which suffered from spontaneous hypertension. Apparently, rosela extract fixes the aorta ring vasolidator response. Vasolidator has the function to widen the blood vessel so as to accelerate the blood circulation.