Abstract
In this case, Esophagogastroduodenoscopy showed an approximately 25-mm diameter annular and polypoid mucosa at the opposite side of Pylorus ring in first part of duodenum. The biopsy specimens were diagnosed with the heterotopic gastric mucosa (HGM) pathologically. This is a rare presentation of annular and polypoid HGM in duodenum. This may indicate the needs for other documents as well as analysis regarding the mechanism for the development of HGM in duodenum.