Purpose: To detect the mRNA expression of epithelial skeleton protein CK19 in the peripheral blood of patients with colorectal cancer; to study its relationship to other clinicopathological parameters; and to discuss if the detection can help post-operative adjuvant therapy. Methods: A total of 39 blood samples from colorectal cancer patients were included in the study. Specific RT-PCR primers were used to avoid the amplification of pseudogenes. Results: Of 39 patients 31 showed CK19 mRNA expression (79.5%) . The patients in Dukes stage C and D showed higher frequency of CK19 mRNA expression than that in Dukes A and B (P