We report a case of relapsing pancreatitis in familial adenomatous polyposis (FAP) with severe duodenal adenomatosis (Spigelman's stage IV). A 58-year-old man who had undergone total colectomy for FAP 18 years earlier was hospitalized for carcinoma arising from the residual rectum. He had experienced several episodes of upper abdominal pain and ultrasonography and computed tomography (CT) showed diffuse calcification of the atrophic pancreas, suggestive of chronic pancreatitis. He had severe diabetes mellitus, but had no symptoms of pancreatic exocrine dysfunction. Upper endoscopy showed multiple duodenal adenomas including carcinoma involving the papilla of Vater. To remove these duodenal adenomas and ampullary carcinoma and prevent recurrent pancreatitis, we performed pancreaticoduodenectomy. On pathologic examination, the major duodenal papilla was completely obstructed by the carcinoma, and the minor papilla was also involved by the adenoma. The patient has no evidence of disease and has experienced no pancreatitis in 3 years of follow-up.