Abstract: Objective To investigate cyclooxygenase-2 (COX-2) expression of in colorectal carcinoma cell lines and tissues and its clinical implications. Methods SP immunohistochemistry was used to detect COX-2 protein in SW480 and SW620 cell lines and 50 primary colorectal carcinoma and 50 lymphoma metastasis carcinoma specimens. Real-time PCR was used to detect COX-2 mRNA expression in SW480 and SW620 cell lines. Results SW480 and SW620 cell lines both highly expressed COX-2. The positive expression levels of COX-2 increased significantly in lymph node metastatic carcinoma in comparison with primary colorectal carcinoma (P<0.05). The expression COX-2 mRNA in SW620 cell line was higher than that of SW480 cell line, showing a mean expression increment of 2.268 folds in SW620 cell line relative to SW480. Conclusion Elevated COX-2 expression may be associated with lymph node metastases of colorectal carcinoma.