Abstract: Objective　To investigate the correlations of the serum cystatin C（Cys C），serum creatinine（SCr），some important kidney pathological changes and clinical indices，and to provide more reference for the clinical application of Cys C.  Methods　A total of 260 patients with kidney biopsy were enrolled randomly. The correlations of Cys C，SCr and kidney disease severity (global sclerosis，renal tubular atrophy and interstitial fibrosis) score，age and hemoglobin (Hb) were analyzed. The patients were classified into 5 groups according to the global sclerosis 0-4 points，were classified into 4 groups according to the renal tubular atrophy 0-3 points，and were classified into 4 groups according to the interstitial fibrosis 0-3 points. The Cys C and SCr changes were compared among the various pathological groups.  Results　Cys C with SCr，global sclerosis，renal tubular atrophy，interstitial fibrosis and age showed a significant positive correlation（r=0.850,0.471,0.592,0.610 and 0.197，P＜0.01），and SCr with global sclerosis，renal tubular atrophy and interstitial fibrosis showed a significant positive correlation（r=0.501,0.595 and 0.607,P＜0.01），but there was no correlation between SCr and age（r=0.118,P＞0.05）. Cys C and SCr had a significant negative correlation with Hb（r=-0.448 and -0.369，P＜0.01）. The differences of Cys C and SCr among the various pathological groups were statistically significant（P<0.01）. With the increasing of pathological damage degrees，the Cys C and SCr levels also increased，but when pathological damage degrees reached 1-2 points （<50%），the Cys C level of most patients reached or exceeded the upper limit of the reference range，however the SCr levels of most patients were still in the reference range.  Conclusions　Cys C and SCr can reflect the kidney pathological damage and renal functional status of patients. Cys C is superior to SCr in the sensitivity of evaluating early renal injury. However，both of them have influence factors. When choosing the indices for evaluating kidney function，the influence factors of patients should be considered for reference，then when necessary，they can be associated with several indices to improve the accuracy of evaluating kidney function.

Key words: Cystatin C, Creatinine;Pathology, Kidney failure, Glomerular filtration rate, Nephrosis