MAGE-A9 is a novel member of the melanoma-associated antigen (MAGE) family and is expressed in testicular cancer. The present study investigated MAGE-A9 expression as a potential biomarker in colorectal cancer (CRC). Immunohistochemical analysis was used to determine the expression of MAGE-A9 in 201 cases CRC tissues. We used quantitative real-time polymerase chain reaction (RT-PCR) and western blot analysis to further verify the results. The correlation between MAGE-A9 expression, clinicopathological features and prognosis of CRC patients was analyzed. The results showed that MAGE-A9 was predominantly localized in the cytoplasm of cancer cells and stromal cells. Compared to normal adjacent tissues, the high expression rate of MAGE-A9 in CRC tissues was significantly increased (P<0.001). High MAGE-A9 expression was significantly associated with venous invasion (P=0.008) and lymph node metastasis (P<0.001). The survival rate of the CRC patients who were positive for MAGE-A9 expression was significantly lower than that of CRC patients with negative MAGE-A9 expression. Moreover, univariate and multivariate analyses showed that high MAGE-A9 expression was a poor prognostic factor for CRC patients. Hence, MAGE-A9 is expected to become a new target for CRC treatment.