Neurofibromatosis type 1 (NF1; also known as von Recklinghausen's neurofibromatosis) is inherited in an autosomal dominant fashion, although it can also arise due to spontaneous mutation. Gastrointestinal involvement of NF1 is seen in 10% to 25% and causes symptoms in fewer than 5%. Histologically, the gastro intestinal (GI) manifestation of NF1 occurs in three forms: hyperplasia of the gut neural tissue, stromal tumors, and duodenal or periampullary endocrine tumors. A 31-year-old female, diagnosed with NF1, presented with poor oral intake and vomiting for 10 days prior to admission. Preoperative gastrofiberscopic finding was gastric outlet obstructing polypoid duodenal bulb lesion. The patient underwent hemigastrectomy with antecolic gastrojejunostomy due to gastric outlet obstruction. The final pathologic report was submucosal neurofibromatous proliferation with Brunner's gland hyperplasia located at the duodenal bulb in the NF1 patient. We report this case with a review of literatures.