ABSTRACT. Herein, correlations between expression levels of CK20 and efficacy of treatment and postoperative prognosis of colorectal cancer were evaluated to elucidate the clinical value of CK20. Postoperative follow-up was performed on 62 patients who underwent surgery for colorectal cancer between January 2010 and December 2010. Samples of tumor tissues and intraperitoneal drainage fluids were collected. Blood samples were obtained during the 2-year follow-up period. The expression of CK20 in surgical specimen, intraperitoneal drainage fluids, and postoperative serum samples was quantified by enzyme-linked immunosorbent assay, RT-PCR, and western blotting. Correlation between the levels of CK20 and postoperative outcomes was investigated by Spearman correlation analysis. In both tumor specimens and intraperitoneal drainage fluids, CK20 levels were lower in patients with earlier cancer stages than in those at later stages. During postoperative follow-up, serum negative CK20 patients had significantly higher 3-year survival rates than serum positive CK20 patients. All differences were statistically significant (P < 0.05). CK20 levels can provide clinically valuable information on the postoperative prognosis of patients with colorectal cancer.