A case of diffuse villous adenoma affecting the pancreatic duct in a 31-year-old woman is described. The diagnosis was made by endoscopic retrograde cholangiopancreatography and the patient treated by proximal pancreatectomy. One year later the patient is alive and well. Papillary tumors affecting the pancreatic duct have rarely been described. All previous cases have occurred in middle-aged or elderly patients. None of the previously described benign tumors was as extensive as the one reported here. The possible pre-malignant potential of such tumors is discussed.