Carcinoma of the ampulla of Vater is closely associated with tubular and villous adenomas of the ampulla. Its prognosis is strongly related to the degree of invasion and nodal involvement. However, the determination of the extent of invasion is not easy. We describe such a case with three-dimensional spread into duodenum and common bile and pancreatic ducts preoperatively detected by hypotonic duodenography, duodenoscopy, endoscopic retrograde cholangiopancreatography, and endoscopic ultrasonography. The histological examination of an endoscopic biopsy specimen revealed only dysplasia. A resected specimen showed carcinoma of Vater’s ampulla with three-dimensional spread, but the invasion was limited to the epithelial and mucosal layer