A 64-year-old woman had a large subcarinal cyst accompanied by high serum carcinoembryonic antigen (CEA) of 55.7 ng/ml removed thoracoscopically. The pathological diagnosis was benign bronchogenic cyst. Immunohistochemical findings clearly showed CEA in the stratified columnar epithelial lining of the cyst. Serum CEA returned to the normal range within 40 days of surgical resection.