Abstract: AIM To investigate the effects of angiotensin converting enzyme inhibitor (ACEI) on apoptosis and the expression of Fas and Fas L in the kidney of diabetic rats. METHODS Uninephrectomized Spraque Dawley rats were used to induce diabetes by intraperitoneal injection of streptozotocin (65 mg·kg^-1 ). Benazepril (10 mg·kg^-1 ) was given daily by gavage from the next day of the induction to diabetes for 12 weeks. Apoptosis was evaluated by means of terminal-deoxynucleotidyl transferase mediated d-UTP nick end labeling ( TUNEL ). Flow cytometry and immunohistochemistry were used to detect the expression of Fas and Fas-L. RESULTS Compared with those in the kidneys of control group, apoptotic cells were more in number and the expression of Fas and Fas-L was higher in the diabetic kidneys ( P <0.05). The number of apoptotic cells and the level of expression of Fas and Fas-L were reduced by benazepril treatment ( P <0.05). CONCLUSION Angiotensin converting enzyme inhibitor benazepril showed some renal protective effect on diabetic nephropathy, party through inhibiting apoptosis by down-regulating Fas and Fas-L expression.