Appendiceal mucinous adenocarcinoma is a rare disease.The preoperative diagnosis is almostly impossible due to the lack of typical symptoms and inexperienced surgeons.One patient with appendiceal mucinous adenocarcinoma was diagnosed successfully at the 210th Hospital of Chinese PLA,who was misdiagnosed as with periappendiceal abscess by other hospitals.The result of intraoperative frozen pathological section confirmed appendiceal mucinous adenocarcinoma.And then the patient received extended resection and effective recovery.