Between June 1990 and April 1991, 62 colorectal tumors were assessed in a prospective fashion on the basis of various tumor characteristics. Parameters included K-ras mutation, overexpression of the p53 protein, and proliferating cell nuclear cell antigen, as well as standard histopathologic examination. A multivariate analysis showed that K-ras mutation correlated with vascular invasion (P < 0.01) and hematogenous metastasis (P < 0.01). With regard to survival time, multivariate analyses using the Cox proportional hazard model suggested that status of lymph node metastasis (P < 0.01, relative risk [rr] = 7.27), TNM stage (P < 0.05, rr = 5.37), lymphatic invasion (P < 0.05, rr = 4.48), and K-ras mutation (P < 0.06, rr = 3.69) are the most independent prognostic factors. We compared the prognostic value of the molecular assays and standard TNM prognostic factors by multivariate analysis.