Objective:To explore the alterations of serum cystatin C in patients with Alzheimer’s disease.Methods:61 inpatients with Alzheimer’s disease and 64 healthy elders matching with age and gender were enrol ed from Jan 2013 to Jun 2011, the level of serum cystatin C was measured by automatic biochemistry analyzer in the two groups. Results:The level of serum cystatin C(0.96±0.37mg/l) significantly decreased in AD group, comparing with the control group(1.09± 0.29mg/l), the dif erence was significant(P<0.05).Conclusion:The level of serum cystatin C decreased,However,the mechanism needs further study.