Abstract: Objective: To explore the value of cystatin C in assessing glomerular filtration rate.Methods: One hundred and nine patients were devided into 4 groups according to the level of endogenous creatinine clearance rate(Ccr),which included normal renal function group(Ccr80 ml /min,n = 33), renal insufficiency compensation group (50 ml /minCcr＜80 ml /min,n = 20), renal insufficiency decompensation group(20 ml /minCcr＜50 ml /min,n = 27)and renal failure group(Ccr＜20 ml /min,n = 29).Sixtynine healthy people were set as control group.The levels of cystatin C,Scr and urea nitrogen in blood plasma of all group were determined,which were statistically analyzed.Results: Compared with control group, there were significant differences in the cystatin C levels of other groups (P＜0.01).The levels of Cystatin C increased along with the Ccr levels decline.There were good relevant relationships between Ccr and Scr (P＜0.01).Conclusions: Blood plasma cystatin C is a sensitive indicator for evaluating the glomerular filtration function,which can replace the role of Ccr.