Coeliac disease (CD) is an autoimmune disorder which leads to chronic inflammation of the gut. Furthermore, CD is associated with upper gastrointestinal malignancies, particularly lymphoma of the small intestine. Besides lymphoma, an increased frequency of associated small bowel carcinoma has been described. Here we report the case of a 70-year-old male suffering from CD who was treated with a gluten-free diet presenting with complaints of nausea, vomiting and weight loss of about 8 kg in two months. He underwent esophagogastroduodenoscopy, which identified distention of the stomach and duodenum and in the pars horizontalis a distinct obstruction was suggestive. However, histopathological examination showed a normal mucosal membrane. Additionally, a computed tomography scan of the abdomen was performed which showed an expanded stomach and duodenum up to the ligament of Treitz. During an explorative laparotomy a small tumor was palpated near the ligament of Treitz. Subsequently, a duodenal segment resection was performed. After surgery, the patient recovered well and left our hospital in good condition.