With progress in diagnostic procedures such as duodenoscopy and endoscopic retrograde cholangiopancre - aticography, early diagnosis of carcinoma of ampulla of Vater has become possible. Early carcinoma of the ampulla of Vater, not infiltrated beyond Oddi's muscle shows excellent postoperative outcome of high curability. A 57 year old female was visited our hospital because of intermittent upper abdominal discomfort. During gastroscopy, shallow ulcerative mucosal lesion of ampulla of Vater was dicovered, and then biopsy was done via duodenoscopy. The biopsy specimen shows adenocarcinoma and successful operation was done. Cancer cells were not infiltrated beyond Oddi's muscle. (Korean J Gastrointest Endosc 2001;22:101 - 104)