To investigate the effect of taurine on hypertension, a rat model of hypertension was produced by administering N-nitro-L-arginine methylester (L-NAME) to reduce the levels of the vasodilator, nitric oxide. At the same time that L-NAME was administered, taurine treated animals received either 1% or 2% taurine in the drinking water. As a control, 1% taurine was added to the water without L-NAME administration in order to investigate the effects of taurine on blood pressure of normal rats. The results showed that taurine increased serum levels of nitric oxide and nitric oxide synthase, inhibited the elevation of blood pressure, interfered with the activity of the renin-angiotensin-aldosterone system and minimized the elevation in serum cytokine, endothelin, neuropeptide Y and thromboxane B2. It also reduced oxygen derived free radical generation, upregulated the antioxidant defenses and inhibited the proliferation of vascular smooth muscle cells. These data indicate that taurine benefits hypertensive rats, with 2% taurine mediating greater improvement than 1% taurine.