Brunner's gland hamartoma is an extremely uncommon benign tumor of the duodenum. Most of the lesions are small, asymptomatic and are detected incidentally. It may rarely attain a large size and produces a variety of clinical manifestations. Imaging modalities and endoscopy may locate the lesion, but definitive diagnosis requires histopathological examination. We report a case of a 58-year-old Omani female who presented with obstruction due to a large Brunner's gland hamartoma.