Objective: To investigate the clinical significance of the measurement of carcinoembryonic antigen (CEA) in abdominal drainage fluid after surgery for colorectal cancer. Methods: The CEA concentration in the serum before surgery and on postoperative day (POD) 1, as well as the CEA concentration on POD 1 in abdominal drainage fluid from 112 colorectal cancer patients were determined, and the CEA concentration on POD 1 in abdominal drainage fluid from 35 patients with benign intestinal disease was used for comparison. The change of serum CEA level before and after surgery in colorectal cancer patients, and the difference in postoperative CEA concentration in abdominal drainage fluid between patients with colorectal cancer and benign intestinal disease were determined, and the relations of the CEA concentration in abdominal drainage fluid with clinicopathologic features in colorectal cancer patients were also analyzed. Results: In the group of colorectal cancer patients, the serum CEA concentration on POD 1 was significantly decreased compared with its level before surgery, and the CEA concentration on POD 1 in abdominal drainage fluid was significantly higher than that in group of patients with benign intestinal disease (both P<0.05). The CEA concentration in abdominal drainage fluid was not associated with the degree of tumor differentiation in colorectal patients (P>0.05), but changed in the same direction as the depth of invasion and clinical stage of the tumor, and was significantly higher in group of patients with lymph node or distant metastases than that in non-metastasis group (all P<0.05). Conclusion: Measurement of the postoperative CEA concentration in abdominal drainage fluid has important predictive value for the outcome of colorectal cancer.