In order to evaluate the usefulness of CA 72-4 tumour-associated antigen assay in colorectal carcinoma, we have studied 70 patients with benign colorectal diseases and 127 patients with colorectal cancer at different stages. The results were compared with those obtained by CEA and CA 19-9. No significant differences were found in any of the stages according to Dukes' classification when comparing stages A, B and C. However, there were differences with CEA (P < 0.001), CA 19-9 (P < 0.001) and CA 72-4 (P < 0.001) when comparing stages A, B and C with stage D. In the ROC curve, at a specificity of 95%, the sensitivities of CEA, CA 19-9 and CA 72-4 were 46.4%, 20.5% and 40.1%, respectively. In conclusion, CA 72-4 showed better sensitivity and specificity scores than CA 19-9. CEA increased individual sensitivity from 46.4% to 59.8% when combined with CA 72-4, showing a decrease of merely 0.9% in specificity.