Introduction: We present a case of gastric outlet obstruction from a large 10cm duodenal mass as the first presentation of Peutz-Jegher syndrome. Case report: A 21-year-old female, migrant from Pakistan, presents with acute-on-chronic symptoms of post-prandial vomiting, early satiety, distension and a 5kg weight loss in the last 2 months. She has had long-standing symptoms of vomiting after food for the last 7 years but declined endoscopic examination in Pakistan. She has no known significant illness and has no family history of any gastrointestinal problems. On examination, she was pale, thin with a BMI of 13. There was classical mucocutaneous hyperpigmentation of the lips. The abdomen was non-distended with a palpable mass in the RUQ. There are no visible surgical scars. Radiological investigations (US and CT) showed a large 7x7x10cm duodenal mass with multiple small bowel polyps (at least 5) with 2 polyps complicated by intussusception. In this index admission, she undergone two exploratory laparotomies for small bowel resection and emergency pancreaticoduodenectomy. Histology of the large duodenal polyp confirms pancreatic cancer and small bowel polyps consistent with Peutz-Jegher syndrome. Discussion: Peutz-Jeghers syndrome (PJS) is a rare autosomal dominant disease, caused by a germline mutation in the serine/threonine kinase 11 gene. It predisposes patients to development of multiple gastrointestinal hamartomatous polyps, mucocutaneous pigmentations and an increased risk of a variety of cancer. Early screening for the associated malignancies are strongly recommended in patients with PJS.