COX-2 is overexpressed in colorectal tumour tissue relative to the healthy colonic mucosa, thus we investigated the prognostic significance of COX-2 in determining the metastasis of patients with colorectal cancer. PubMed, EMBASE, and Cochrane Library were searched using the following terms colorectal cancer, colon cancer, rectal cancer, colorectal carcinoma, Cyclooxygenase-2, and prognosis to identify articles providing information on the prognostic importance of COX-2 in adult patients with metastatic colorectal cancer. Review papers, non-research letters, comments, case reports, animal studies, original research with sample sizes of fewer than 20, case reports and series, non-English language articles, and pediatric studies (those under the age of 17) were excluded. The Newcastle Ottawa Scale (NOS) was used to assess the credibility of the included studies. The full texts were evaluated and this study complied with the terms of the local protocol and the Helsinki Declaration. Eight relevant studies were included in this review involving 937 patients. The meta-analysis revealed that COX-2 expression is associated with lymph node invasion (RR 1.85 [1.21, 2.83], P = 0.005, I2 = 88 %) and liver metastasis (RR 4.90 [1.12, 21.57], P = 0.04, I2 = 42 %), but not with venous dissemination (RR 1.48 [0.72, 3.03], P = 0.28, I2 = 87 %). COX-2 expression is associated with lymph node invasion in colorectal cancer but further studies are required to determine the prognostic significance of COX-2 expression in determining metastasis status for colorectal cancer patients.