Objective The aim of the study was to investigate the discrepancy in nucleolin expression between colon adenoma and colon adenocarcinoma,explore the role of nucleolin expression in the carcinogenesis of colon adenocarcinoma,and determine the correlation of the nucleolin expression level with histological grade in colon adenocarcinoma.Methods In total,80 cases of colon adenocarcinoma with cancer-adjacent colon mucosa and 60 cases of colon adenomas were examined by immunohistochemistry using an antibody against nucleolin.Nucleolin expression levels in these groups were compared.The correlation between the nucleolin expression level and grade of colon adenocarcinoma was analyzed.Results Nucleolin expression is located in the nuclei of colon adenocarcinoma,colon adenoma,and cancer-adjacent colon mucosa tissues with different intensities.A semiquantitative evaluation using the Allred scoring system showed that the nucleolin immunostaining score in colon adenocarcinoma(7.8 ± 0.1) was significantly higher than those in colon adenoma(6.3 ± 0.2) and cancer-adjacent colon mucosa(5.4 ± 0.1;P < 0.01).The nucleolin immunostaining score in colon adenoma was significantly higher than that in cancer-adjacent colon mucosa(P < 0.01).Nucleolin expression levels in well-differentiated and moderately differentiated adenocarcinoma(6.8 ± 0.2) were significantly lower than those in poorly differentiated adenocarcinoma(8.0 ± 0.1;P < 0.01).Conclusion Increased nucleolin expression may play an important role in the process of malignant transformation of colon adenocarcinoma and predicts a poor prognosis. Objective The aim of the study was to investigate the discrepancy in nucleolin expression between colon adenoma and colon adenocarcinoma, explore the role of nucleolin expression in the carcinogenesis of colon adenocarcinoma, and determine the correlation of the nucleolin expression level with histological grade in colon adenocarcinoma. Methods In total, 80 cases of colon adenocarcinoma with cancer-adjacent colon mucosa and 60 cases of colon adenomas were examined by immunohistochemistry using an antibody against nucleolin. Nucleolin expression levels in these groups were compared. The correlation between the nucleolin expression level and grade of colon adenocarcinoma was analyzed. Results Nucleolin expression is located in the nuclei of colon adenocarcinoma, colon adenoma, and cancer-adjacent colon mucosa tissues with different intensities. A semiquantitative evaluation using the Allred scoring system showed that the nucleolin immunostaining score in colon adenocarcinoma (7.8 ± 0.1) was signif icantly higher than those in colon adenoma (6.3 ± 0.2) and cancer-adjacent colon mucosa (5.4 ± 0.1; P <0.01). The nucleolin immunostaining score in colon adenoma was significantly higher than that in cancer- adjacent colon mucosa ). Nucleolin expression levels in well-differentiated and moderately differentiated adenocarcinoma (6.8 ± 0.2) were significantly lower than those in poorly differentiated adenocarcinoma (8.0 ± 0.1; P <0.01) .Conclusion Increased nucleolin expression may play an important role in the process of malignant transformation of colon adenocarcinoma and predicts a poor prognosis.