The frequency of duodenal adenomas in patients with, familial adenomatous polyposis is high. Duodenal adenoma has malignant potential, and duodenal adenocarcinoma is one of the main causes of death in patients who have had previous proctocolectomy. A conservative approach to the treatment of duodenal adenomas (nonsteroidal anti-inflammatory drugs, endoscopy, polypectomy through duodenotomy) is inefficient and unsafe. When invasive cancer occurs in duodenal adenomas, the result of surgery is poor. We have performed prophylactic pancreaticoduodenal resection (PDR) for nonmalignant severe duodenal polyposis in five patients since 1991. No operative mortality was observed. One patient developed a pancreatic fistula which was successfully managed by medical treatment. The mean follow-up was 35 months. All five patients are still alive and have a good functional outcome. Prophylactic PDR may be indicated in familial adenomatous polyposis when duodenal polyposis is severe. Stages III and IV of Spigelman's classification, periampullary adenoma, age above 40, and family history of duodenal cancer are factors that may lead to the decision to perform prophylactic PDR.