Abstract: Objective To understand the CEA mRNA relative expression in the per ipheral blood and lymphnodes in patients with different stages of colon cancer and its use for preoperative diagnosis and staging of the colon cancer.Methods Real-time RT-PCR was adopted to detect the CEA mRNA expression in lymphnode and in peripheral blood of 10 normal individuals and 40 colon cancer patients.Results CEA mRNA positive rate was 87.5% in peripheral blood in 40 preopera tive patients.No CEA mRNA was detected in 10 normal individuals,and the difference was significant.The positive CEA mRNA expression in the lymphnodes of A+B stage cancer was 15.8%,and C+D stage was 53.3%.Clinical stage was closely related to the positive CEA mRNA expression and the difference was sign ificant(χ²=5.4,P<0.05).The positive CEA mRNA expression in the peripheral blood of C+D stage colon cancer patientsw as higher than that of A+B stage,but the difference was not significant(χ²=0.75,P>0.05).Conclusion The CEA mRNA expression in the peripheral blood of patients with colon cancer is higher than that of normal individuals.The results is use ful for the preperative diagnosis of colon cancer.Positive CEA mRNA expression in the lymphnodes is related to different clinical staging and can be used as the reference of clinical stage of colon cancer.