Brunner's gland adenoma is a rare benign tumour of the duodenum. His most common location is the posterior wall of the duodenum near the junction of its first and second portion. It is usually small and asymptomatic often discovered incidentally with upper gastrointestinal endoscopy, but sometimes may become large causing symptoms (haemorrhage or intestinal obstruction). We report a rare case of a very large Brunner's gland adenoma in a 38-year-old female presenting with severe anaemia but without obstructive symptoms and detected by ultrasonography. The tumour was managed by surgical removal and during a six month follow-up the patient reimaned symptom-free without any recurrence. The literature on Brunner's gland adenoma is reviewed.