Objective To observe the effects of angiotensin Ⅱ(Ang Ⅱ)blockade on renal function, renal blood flow and renal oxygen consumption in chronic renal failure (CRF) rats induced by 5/6th kidney ablation /infarction (5/6A/I). Methods Sprague-Dawley rats were randomly divided into 3 groups: the normal group (group A, n =14), model group (group B, n=14) and angiotensin II blockade (Cozaar with Monopril) treatment group (group C, n =14). The chronic renal failure (CRF) rat models were induced by 5/6th kidney ablation/infarction. The tail artery systolic pressure (SBP), diastolic blood pressure (DBP) and tail vein serum creatinine (Scr), blood urea nitrogen (BUN), hemoglobin (Hb) and creatinine clearance rate (Ccr) were assessed before and after intervention. The course of treatment was sixty days. The renal blood flow (RBF), blood gas analysis of abdominal aortic and renal vein, left renal vein pressure (RVpO₂) were detected and remnant renal oxygen consumption (QO₂ /T_Na) was calculated, and the pathological changes of remnant kidney were observed after the 60 d intervention. Results (1) Compared with the group A, the levels of Scr, BUN and tail artery SBP, DBP were significantly increased (P<0.01 for all), and the levels of Ccr and Hb were significantly decreased (P<0.01) in the groups B and C, demonstrating the successful modeling. (2) Compared with the group B, the levels of Scr, tail artery SBP, DBP and QO₂/T_Na were significantly decreased (P<0.01 for all), the levels of BUN were decreased (P<0.05), the levels of Hb, Ccr and RVpO₂ were significantly increased (P<0.01 for all), the level of RBF was increased (P<0.05) in the group C after intervention.(3) The histopathological examination of the remnant renal tissue showed that the pathological changes in the group C were apparently reduced, better than those of the Group B. Conclusions Angiotensin II blockade can increase RBF, reduce renal oxygen consumption, improve renal function, and reduce the renal pathological changes in CRF rats. The mechanism of renal protection may be related to the regulation of cellular energy metabolism and improvement of renal oxygen consumption.