Abstract: OBJECTIVE To investigate the effect of puerarin on endothelial function in angiotenin (Ang) Ⅱ-induced hypertensive rats as well as the underlying mechanism of improving endothelial function. METHODS SD rats were randomly divided into control, Ang Ⅱ and puerarin groups. The rats of Ang Ⅱ groups were infused with Ang Ⅱ (0.7 mg·kg^-1·d^-1 implanted by mini-pump) for 5 d while the rats of puerarin group were treated with puerarin (100 mg·kg^-1·d^-1) for 10 d followed by Ang Ⅱ and puerarin for 5 d. The systolic blood pressure (SBP) was measured by tail-cuff method. Endothelium-dependent relaxation (EDR) to acetylcholine was determined using organ chamber bath. Expression of the protein in the aortic tissue was determined by Western blot analysis. RESULTS Puerarin significantly reduced SBP (P<0.05), aortic and LV hypertrophy in Ang Ⅱ-infused rats. Puerarin also reduced aortic medial thickness and myocardial cell surface area in Ang Ⅱ-infused rats. Compared with the rats in control group, Ang Ⅱ infused rats exhibited an impaired EDR with reduction in the protein expression of phosphor-eNOS at ser 1177 and increase the expression of gp91phox (85%), p22phox (113%). Puerarin improved EDR and reversed the changes of Ang Ⅱ-induced protein expression of above molecules. CONCLUSION Puerarin reduced blood pressure, improved endothelial function and end organ damage in Ang Ⅱ-induced hypertensive rats, the anti-oxidant and upregulation of phosphor-eNOS of puerarin may in part contribute to its cardiovascular protective effects.