Abstract： Objective To investigate the relationship between apoptosis and the expression of Bax and Bcl 2 in the kidney of diabetic rats. Methods Uninephrectomized SD rats were used to induce diabetes by intraperitoneal injection of STZ (65 mg/kg). Apoptosis was evaluated by means of terminal deoxynucleotidyl transferase mediated d UTP nick end labeling (TUNEL). Flow cytometry, immunohistochemistry and in situ hybridization were used to detect the protein and mRNA of Bax and Bcl 2. Parameters of renal function such as excretion of urinary protein, BUN, Ccr were also detected. Results Compared with those in the kidneys of control group, apoptotic cells were more in number and the expression of Bax and Bcl 2 was higher in the diabetic kidneys at week 2,4,8,12 ( P <0.05). Further, the number of apoptotic cells and the Bax/Bcl 2 ratio increased gradually ( P <0.05), and they were significantly correlated. Conclusion Apoptosis in the diabetic kidney may play a role in the progression of diabetic nephropathy. The change in Bax and Bcl 2 activities may be responsible for apoptosis in diabetic kidney.