To investigate the role and mechanisms of apoptosis and apoptosis signaling pathway in 5/6 nephrectomy rat model (SNx), the mRNA and protein levels of caspase-3, -8, -9 and apoptosis were detected by in situ end labeling ( TUNEL ), immunohistochemistry, RT-PCR, Western-blotting 1,2, 4, 8, 12, 16, 26 and 40 weeks after 5/6 nephrectomy rat model was made respectively. The rats in the model group developed glomerular sclerosis and renal interstitial fibrosis. The number of the apoptototic cells in glomeruli, renal tubule and renal interstitium was remarkably higher in the model group than that in the control group (P＜0.05, P＜0.01). Changes of mRNA and protein level of caspase-3, -8, -9 had the same tendency and was up-regulated wavily in the rat model compared with the control group (P＜0.05). Peaks in model appeared on the 4th and the 40th week respectively. The growth amplitude of caspase-9 was remarkably higher than that of caspase-8. It is concluded that the development of 5/6 nephrectomy rat model was correlated with the apoptosis of glomeruli, renal tubule and renal interstitium. Both of death receptor and mitochondria signaling pathways are involved in the process and the latter might play a primary role.