OBJECTIVE Information on cellular proliferation is gaining importance for predicting prognosis in several cancers. To clarify the clinicopathological significance of argyrophilic nucleolar organizer region (AgNOR), proliferating cell nuclear antigen (PCNA), and DNA ploidy pattern, we studied their correlations with clinicopathological factors in colorectal cancer. METHODS Fifty-two patients with colorectal cancer were examined by AgNOR staining, immunohistochemical study of PCNA expression, and DNA flow cytometry. RESULTS The AgNOR score and the PCNA labeling rate (PCNA LR) were significantly higher in patients with deep invasion (P = 0.0072, P = 0.0355), liver metastasis (P = 0.0022, P = 0.0001), and Dukes D classification (P = 0.0002, P = 0.0001) than in patients without these factors. In patients with high AgNOR score (>3.83) or with high PCNA LR (>48.8), prognosis was significantly worse (P = 0.0002, P = 0.0123) than in those with low AgNOR score (<3.83) or in those with low PCNA LR (<48.8), respectively. No significant association was observed between AgNOR score and PCNA LR. Combined analysis revealed that the survival curve for patients with high AgNOR score and high PCNA LR was significantly lower (P = 0.0156) than that for patients with high AgNOR score and low PCNA LR. There was no significant correlation between DNA ploidy pattern and clinicopathological findings. CONCLUSIONS PCNA LR and AgNOR score were correlated not only with local progression but also with metastasis. Their determination provided useful prognostic information, and these parameters are probably independent. Their simultaneous determination was useful for accurate evaluation of prognosis. The value of DNA ploidy pattern was uncertain.