In colorectal cancer, stage is considered to be the strongest prognostic factor, but also serum tumour markers have been reported to be of prognostic value. The aim of our study was to investigate the prognostic value of serum carcinoembryonic antigen (CEA), CA 19-9, CA 242, CA 72-4 and free β subunit of human chorionic gonadotropin (hCGβ) in colorectal cancer. Preoperative serum samples were obtained from 204 colorectal cancer patients, including 31 patients with Dukes' A, 70 with Dukes' B, 49 with Dukes' C and 54 with Dukes' D cancer. The serum levels of CEA, CA 19-9, CA 242 and CA 72-4 were measured with commercial kits with cut-off values of 5 μg/L for CEA, 37 kU/L for CA 19-9, 20 kU/L for CA 242 and 6 kU/L for CA 72-4. The serum hCGβ was quantitated by an immunofluorometric assay (IFMA) with 2 pmol/L as a cut-off value. Survival analyses were performed with Kaplan-Meier life tables, log-rank test and Cox proportional hazards model. The sensitivity was 44% for CEA, 26% for CA 19-9, 36% for CA 242, 27% for CA 72-4 and 16% for hCGβ. The overall 5-year survival was 55%, and in Dukes' A, B, C and D cancers the survival was 89%, 77%, 52% and 3%, respectively. Elevated serum values of all markers correlated with worse survival (p < 0.001). In Cox multivariate analysis, the strongest prognostic factor was Dukes' stage (p < 0.001), followed by tumour location (p = 0.002) and preoperative serum markers hCGβ (p = 0.002), CA 72-4 (p = 0.003) and CEA (p = 0.005). In conclusion, elevated CEA, CA 19-9, CA 242, CA 72-4 and hCGβ relate to poor outcome in colorectal cancer. In multivariate analysis, independent prognostic significance was observed with hCGβ, CA 72-4 and CEA. © 2002 Wiley-Liss, Inc.