Dietary hypertension induced by feeding cholesterol and vitamin D3 in rats for 7 weeks was prevented by the addition of fursulthiamine and diallyl disulfide in the diet. In the isolated preparation of the hypertentive rats, the contractile forces were potentiated by norepinephrine, serotonin and potassium chloride, as compared to that of the normotensive rats. However, the increased contractile forces of the hypertensive rats were inhibited in the aorta of the rats fed with fursulthiamine. Decreases in triglyceride contents were observed in the sera of the hypertensive rats fed with fursulthiamine. Therefore, it is suggested that dietary hypertension in rats may be prevented by supplement of fursulthiamine in the diet.