Endothelin-1 (ET-1) and Angiotensin II (Ang II) play important roles in generatinghypertension. The present work was investigated the hemodynamic and renal effects ofboth ET-1 and Ang II on 2K1C rats. The design of this study included five groups of rats:Group 1 Sham rats, Group 2 Normotensive rats (2K1C(n)), Group 3 two kidney one cliphypertensive rats (2K1C(h)), Group 4 two kidney one clip hypertensive rats + Bosentan(2K1C(h) + Bosentan), and Group 5 two kidney one clip hypertensive rats + Losartan(2K1C(h) + Losartan). Systolic blood pressure (SBP) was significantly elevated in 2K1C(h)rats from third to sixth week after surgery compared with control rats. SBP significantlyfell in bosentan and losartan treated rats. Serum nitric oxide (NO) level in hypertensiverats was slightly decreased, whereas in losartan group it was significantly increased.Serum malonaldehyde (MDA) significantly increased in bosentan treated rats ascompared to hypertensive rats. Bosentan administration caused a markedly increased inNa+excretion rate compared with 2K1C(h) rats in week four after surgery. In conclusion,losartan is more potent than bosentan in reducing hypertension via elevation of serumNO level.