Gamrosu was originally conceptualized from Jeho-tang, a selected thirst quencher of the kings in Chosun Dynasty and Saeng-Maek-san, a qi-vigorating summer beverage recommended by Dongeuibogam. It is a modified fasting therapy beverage which is manufactured from the single herbal medicines composed of those two prescriptions. This study was conducted on 6 obese patients with hypertension. A modified fasting therapy with Gamrosu was practised on them for 10 consecutive days. After the therapy, their average blood pressures were descended from 148/89 mmHg to 119/79 mmHg. The modified fasting therapy with Gamrosu is supposed to be more effective than general diet program or dietary sodium reduction on controlling hypertension. And, Gamrosu improves anti-hypertensive effect by reducing the side effects, such as fatigue, electrolyte imbalance, heartburn, nausea, and headache, during the modified fasting therapy.