AIM: To evaluate the serum levels of cytokeratins and carcinoembryonic antigen (CEA) in diagnosis, staging and prognosis of patients with colorectal adenocarcinoma.METHODS: The sample consisted of 169 patients. One hundred blood donors formed the control group. Radical surgery was performed on 120 patients, with an average follow-up duration of 22.3 mo. Relapses occurred in 23individuals after an average of 18.09 mo. CEA was assayed via the Delfia(R) method with a limit of 5 ng/mL. Cytokeratins were assayed via the LIA-mat(R) TPA-M Prolifigen(R) method with a limit of 72 U/L.RESULTS: In the diagnosis of patients with colorectal adenocarcinoma, CEA showed a sensitivity of 56%, a specificity of 95%, a positive predictive value of 94%, a negative predictive value of 50% and an accuracy of 76.8%.TPA-M had a sensitivity of 70%, a specificity of 96%, a positive predictive value of 97%, a negative predictive value of 66% and an accuracy of 93.6%. The elevation of one of the markers was shown to have a sensitivity of 76.9%, a specificity of 91%, a positive predictive value of 93.5%, a negative predictive value of 70% and an accuracy of 83.6%.There was no variation in the levels of the markers according to the degree of cell differentiation while there was an elevation in their concentrations in accordance with the increase in neoplastic dissemination. There was a statistically significant difference between the patients with stage Ⅳ lesions and those with stages Ⅰ, Ⅱ and Ⅲ tumors.With regard to CEA, the averagelevel was 14.2 ng/mL in patients with stage Ⅰ lesions, 8.5 ng/mL in patients with stage Ⅱ lesions, 8.0 ng/mL in patients with stage Ⅲ lesions and 87.7 ng/mL in patients with stage Ⅳ lesions. In relation to TPA-M, the levels were 153.1 U/L in patients with stage Ⅰtumors, 106.5 U/L in patients with stage Ⅱ tumors, 136.3 U/L in patients with stage Ⅲ tumors and 464.3 U/L in patients with stage Ⅳ tumors. There was a statistical difference in patients with a high CEA level in relation to a shorter survival(P＜0.05). However, there was no correlation between patients with high TPA-M levels and prognostic indices of patients undergoing radical surgery.CONCLUSION: Cytokeratins demonstrate a greater sensitivity than CEA in the diagnosis of colorectal adenocarcinoma.There is an increase in the sensitivity of the markers with tumor dissemination. Cytokeratins cannot identify the worse prognosis in patients undergoing radical surgery.Cytokeratins constitute an advance in the direction of a perfect tumor marker in the treatment of patients with colorectal cancer.