An unusual case of early duodenal carcinoma probably arising in the adenoma of the duodenum is presented. A 64 year old female was seen at the First Department of the Internal Medicine, Iwate Medical University, because of anemia and epigastric discomfort, stool examination showed positive occult blood. A barium examination of the duodenum revealed long mucosal folds running through the second portion. The folds began at near the papilla of Vater and reached to the portion of the ligament of Treitz where a mulberry like tumor, 4 cm. in diameter, was seen. Duodenof iberscopy revealed that the tumor was a pedunculated polyp. The head of the polyp was found in the third portion and the base of the stalk was near the papilla of Vater. The polyp showed strawberry like appearance with reddish and nodular surface. Histologically the large part of the polyp consisted of adenoma, whereas carcinomatous change was recognized in the upper part of the tumor. The invasion of the stalk could not be detected. The diagnosis of the early duodenal carcinoma (cancer in adenoma) was made, and malignant change of the adenoma tissue was suspected. There is no evidence of recurrence one year later. This case is considered to be of value on the point that carcinoma originated from adenoma of the duodenum.