Objective To observe the incidence and pathological characteristics of chronic progressive nephropathy (CPN) in rats and to accumulate valuable data for the study of rat CPN. Methods Sixty imported SD rats, 120 domestic SD rats and 120 domestic Wistar rats were fed imported food, another 120 domestic Wistar rats were fed domestic food. The animals were euthanized after feeding for 104 weeks. The kidneys were collected for conventional histopathological examination. The incidence and pathological characteristics of CPN were observed in relation to different rat strains, genders and foods. Results Glomerular basement membrane and mesangial hyperplasia with segmental sclerosis were the first lesions of CPN, while basophilic changes (degeneration and regeneration) of the renal tubular epithelium with renal interstitial fibrosis were secondary changes. The total incidence rate of CPN was 31. 87%, with 48. 5% in male rats and 15. 1% in female rats. The CPN incidence rate in Wistar rats was higher than in SD rats. The CPN incidence rate in imported SD rats was higher than in domestic SD rats. The CPN incidence rate was higher in rats fed with a higher protein level than a lower protein level. Conclusions Glomerular changes occur first, leading to secondary tubular changes. There is a high incidence rate of CPN in rats, and there are differences in incidence with gender, strain and fodder.