Abstract： Objective To study the diagnostic value of combined detection of three serum tumor markers in patients with colorectal cancer.Methods Between January 2010 and September 2012,120 patients with colorectal cancer in the Third Hospital,Hebei Medical University (observation group),80 patients with benign colorectal diseases (benign control group) and 100 individuals who underwent health check-up (healthy control group) were recruited.The Roche Elecsys 2010 automatic electrochemical luminescence instrument was employed to detect the levels of carcinoembryonic antigen (CEA),carbohydrate antigen(CA) 199 and CA242 in peripheral blood,which entailed comparison on the difference among various TNM stages and analysis of the assay sensitivity and specificity of their combination.Results The observation group yielded significantly higher levels of CEA,CA199 and CA242 compared with benign and healthy control group.The levels of these indices followed the order of TNM Ⅰ,Ⅱ,Ⅲ and Ⅳ respectively,based on the staging.The combination of three indices yielded the assay sensitivity and specificity of 80.00％ and 97.78％,which were higher than those of either parameter alone (CEA:17.50％ and 73.89％,CA199:29.17％ and 67.22％,CA242:71.67％ and 68.89％,all P＜0.05).Conclusion The combined detection of CEA,CA199 and CA242 improves the assay sensitivity and specificity of colorectal cancer and is worthwhile for clinical practice.