A 29-year-old woman was hospitalized with a 1-month history of postprandial epigastric pain, nausea, and vomiting. An upper gastrointestinal tract X-ray series showed a marked narrowing of the pyloric region. A histological examination of duodenal mucosal biopsy samples showed granulomatous inflammation, and thus a diagnosis of intrinsic duodenal Crohn's disease was made. A second upper gastrointestinal tract X-ray revealed a persistent gastric outlet obstruction. At laparotomy, the duodenal wall was found to be thickened over a distance measuring 3.5 cm in length from the pyloric ring. A longitudinal incision was made over the entire length, up to 5.5 cm beyond the pyloric ring on either side, while Finney-type anastomosis was also performed. A postoperative upper gastrointestinal tract X-ray showed an improvement in the gastroduodenal passage. Enteral nutrition therapy was provided postoperatively. Omeprazole was administered at a dose of 20 mg/day for 2 months. The patient currently remains on maintenance therapy with famotidine at 20 mg/day and is clinically doing well.