Carcinoembryonic antigen (CEA) is recommended as a serologic marker to monitor colorectal carcinoma recurrence. Elevations of CEA due to causes other than carcinoma exist and may lead to a misdiagnosis of recurrent carcinoma. We report a case of bowel sequestration with mucocele formation at the site of previous colo-colic anastomosis causing a mild elevation in CEA. The patient exhibited increasing CEA levels 6 years after resection of a sigmoid colon carcinoma with end-to-end anastomosis. Subsequently, computed tomographic and positron emission tomographic scans documented the presence of a cystic mass showing increased uptake at the anastomotic site. At exploratory laparotomy a mass lesion with mucus-filled protrusions was resected. Pathologic examination documented the presence of sequestration of a segment of the bowel wall with a mucocele and no overlying defect at the mucosal anastomotic site by demonstrating the presence of all bowel layers. After resection of the lesion, the CEA level normalized.