PURPOSE: Carcinoembryonic antigen (CEA) is the most widely used tumor marker for detecting colorectal cancer. This study was designed to evaluate the level of serum CEA that is associated with recurrence after potentially curative surgery for colorectal cancer. METHODS: We retrospectively investigated the pre- and post-operative levels of serum CEA in 246 patients with colorectal cancer and they had undergone potentially curative surgery from 1996 through 2005. RESULTS: The pre-operative CEA level was significantly associated with the number of metastatic lymph nodes, the tumor size and the recurrence rate. The feature that was associated with recurrent disease on multivariate analysis was the pre-operative level of serum CEA. CONCLUSION: In order to detect the recurrence of colorectal cancer, we should closely follow up with frequent checks of the CEA level after surgery for those patients who had a high preoperative CEA level.