Primary mucinous adenocarcinoma of the duodenum is rare. Here we report a case we recently encountered, and we review 16 cases reported in Japan. An 82-year-old Japanese woman was admitted to our hospital complaining of abdominal pain and heartburn. An endoscopic examination revealed a Type 2 tumor in the descending limb of the duodenum, and endoscopically obtained specimens revealed a poorly differentiated adenocarcinoma. We performed a curative pancreatoduodenectomy with lymph node resection, and the surgical specimen revealed that the duodenum was the primary site of the mucinous adenocarcinoma. The patient is currently alive ＞ 1 year after the operation without any evidence of recurrence. Of the 16 patients reviewed, all patients had advanced tumors those depth were T3-T4. 9 patients had lymph node metastasis and 4 patients had peritoneal dissemination at the time of surgery. Since mucinous adenocarcinoma of the duodenum is often progressive cancer at a diagnosis, which is tend to have a worse prognosis than other histological types.