Objective To study the clinical significance by detecting the levels of sera cystatin C(Cys C)in patients with colorectal cancer.Methods We compared the levels of sera cys C detected with the immune rate nephelometry(IRN)in 71 colorectal cancer patients.Then we compared it in 40 healthy persons and 48 colorectal disease patients without cancer to investigate the relationship between the level of cys C and the clinicopathological characteristics.Results The levels of cys C in colorectal cancer patients were much higher than those in the other control groups,and were significantly related to Dukes stages and the tumor differentiated degree.Conclusion The results provide convincing evidence that cys C may contribute to occurrence and development of colorectal cancer.