Abstract: 【Abstract】 Objective To identify the determinants of serum cystatin-C (Cys C) in patients. Methods The medical records of 31235 patients admitted to West China hospital from September to October, 2009 and their first laboratorial test results were examined. Liner regression analyses were performed to determine the association of sex, age, renal function, and metabolic index serum Cys C. One-way ANOVA and LSD tests were performed to determine the association between different diseases and serum Cys C. Results The multiple linear regression equation was obtained: Cys C=0.331 +0.686Crea +0.174Urea +0.119Age +0.068Uric -0.057HDL-C -0.041Sex+0.038eGFR -0.031LDL-C -0.026Glu, with a correlation coefficient of 0.859 and a coefficient of determination of 0.738. The level of serum Cys C varied with different diseases, with urinary diseases showing the highest level followed by vascular and respiratory diseases. Conclusion Serum Cys C is associated with renal function, but not with metabolic index. Cys C tends to rise in patients renal function injury.