Abstract: Objective: To optimize adenovirus vector-based gene therapy and to analyze the expression of the coxsackie and adenovirus receptor (CAR) in normal colon tissues, primary tumors and lymph node metastasis of colon carcinoma. Methods: The expression of CAR in 62 cases of colon carcinoma was detected using immunohistochemistry and the relationship between the expression of CAR and clinicopathologic characteristics was analyzed. Results: Compared with paraneoplastic epithelial tissue of the colon, the expression of CAR was generally downregulated in tumor tissues, whereas for the cases with lymph node metastasis, the expression level of CAR in primary tumor and lymph node metastasis was identical. The expression of CAR was associated with patient age and tumor size. Conclusion: Downregulated expression of CAR is commonly seen in colon carcinoma, suggesting that the influence of CAR expression on therapeutic efficacy should be carefully considered when planning a regimen of gene therapy using adenovirus vector.