A double pylorus, a fistulous communication between the gastric antrum and duodenal bulb, is a very rare anomaly. It appears as an acquired lesion in the majority of cases and mainly occurs in males with chronic obstructive pulmonary disease, chronic renal failure, chronic rheumatism, systemic lupus erythematosus, or diabetes. However, there are no previous reports of a double pylorus combined with diabetes mellitus in Korea. Recently we experienced a case of double pylorus caused by a peptic ulcer in 74-year-old man who had diabetes mellitus with complications. We report this case with a review of the literature. (Korean J Gastrointest Endosc 2008;36:380-384)