Objective To explore the value of cytokeratin-20 (CK-20) mRNA in the clinical diagnosis of rectal cancer.Methods A total of 120 rectal cancer patients to receive surgical treatment in our hospital were selected.Their preoperative peripheral blood was collected to detect the expression of CK-20 mRNA.Pathological analysis was conducted on surgical resection tissues to study the pathological factors affecting the positive expression of CK-20 mRNA.Results The positive expression rate of CK-20 mRNA among rectal cancer patients was 46.67%;tumor diferentation degree,TNM staging,depth of tumor invasion,lymph node metastasis and liver metastasis were the factors that affect the positive expression of CK-20 mRNA.Correlation analysis showed that tumor differentiation degree,TNM staging and depth of tumor invasion were significantly positively correlated to the expression of CKv20 mRNA (P < 0.05).Conclusion The CK-20 mRNA in the peripheral blood of rectal cancer patients is a sensitive index of the micrometastasis of rectal cancer;,tumor differentiation degree,TNM staging and depth of tumor invasion are the major factors that affect the expression level of CK-20 mRNA,which may be used as an important reference index for the detection of rectal cancer prognosis and tumor metastasis prevention.