Carcinoembriogenic antigen (CEA) was widely used as a marker for staging and detection of recurrence and metastases, and evaluation of response of radical opertion or chemotherapy in colorectal cancer patients. METHODS: We examined 50 patients with sigmoid colon and rectal cancer patients who had a radical operation between 1994 May and 1995 April. We checked the level of CEA of peripheral blood preoperatively and postoperatively, and inferior mesenteric vein, bile of gall bladder and peritoneal fluid during surgery. We review clinical characters of the patients, and analyzed the importance of CEA level. RESULTS: The mean CEA levels of peripheral blood (postoperation), inferior mesenteric vein, bile, peritoneal fluid were 5.35+/-2.65, 13.23+/-2.13, 9.23+/-1.65, 7.42+/-2.34 ng/ml respectlively. The mean CEA level of inferior mesentiric vein (13.23+/-2.13 ng/ml) was significantly higher than that of preoperative peripheral blood (8.13+/-2.34 ng/ml) (p<0.05). Falling of postoperative peripheral blood CEA level was also significantly lower than that of preoperative level (p<0.05). CONCLUSIONS: Level of postoperative peripheral blood was related to recurrence rate and survival rate, but tumor size, tumor location, tumor differentiation, Dukes' stage were not related to the CEA level. Bile and peritoneal fluid CEA levels were related with the liver metastasis or local recurrence respectively. We suggest that CEA was useful indicator for evaluation, management, and prognosis of colorectal cancer not only preoperatively but also postoperatively.