Objective To investigate the correlation between serum cystatin C(Cys-C)and renal function in patients with renal damage secondary to cirrhosis.Methods 129 patients with liver cirrhosis were selected,according to the measured glomerular filtration rate (GFR) as the gold standard for evaluation of renal function,patients were divided into group A(cirrhosis with normal renal function),group B(cirrhosis following renal insufficiency),group C (cirrhosis secondary to renal failure).The concentration of Cys-C was compared among three groups,and the serum creatinine(Scr),serum proteins ball micro β2 (β2-MG),creatinine clearance (Ccr) were detected.Results Cys-C,Scr,β2-MG,Ccr and other indicators of A,B,C three groups increased or decreased with the severity of impaired renal function(t =6.65,6.85,6.58,4.54,all P ＜ 0.05).The abnormal detection rates of Cys-C,Scr,Ccr,β2-MG in A group were 31.1％,11.1％,8.9％,26,7％,those in B group were 83.7％,30.2 ％,34.9％,46.5％,those in C group were 100.0％,85.4％,87.8％,95.1％.Conclusion Serum Cys-C concentration is a sensitive marker to evaluate glomerular filtration,it has accurate and reliable clinical significance in the early diagnosis of liver cirrhosis secondary to kidney damage.