Brunner's gland hamartoma is a rare duodenal tumor, which grew larger than 2 cm in diameter in a very limited number of cases. Since the first description in a patient with fatal duodenal intussusception by Cruveilhier in 1835, approximately 143 cases have been reported in the English literature, and only 25 cases had tumor growth to more than 2 cm in diameter. To the best of our knowledge, only 4 cases have been reported in Taiwan. We present three of Brunner's gland hamartomas. In one patient the tumor was located on the secondary portion of the duodenum, which presented with massive tumor bleeding and measured 3.0 cm in diameter. The other two were both located on the duodenal bulb, which presented with abdominal pain and measured 2.0 and 1.3 cm in diameter, respectively. One of the patients received endoscopic ultrasonography which showed specific findings. Two patients received laparotomy and tumor excision; the other one received endoscopic polypectomy. All 3 patients recovered well without any complications.