Gastric surgery is one of the most frequently performed operations in Korea. Retroanastomotic hernia is a rare complication ingastric surgery. We experienced this hernia and herein report it with a review of the literature. A 69-year-old male patient suffered from periumbilical pain for 3 days. Positive physical findings were tenderness around the umbilicus and decreased bowel sound. Simple abdominal findings revealed a mechanical obstruction. This patient had a history of gastrectomy 13 years prior to admission. At operation field, we were able to find the defect consisting of the transverse mesocolon, stomach, jejunum and retroperituneum. In Korea, since its first report by Petersen, only a few reports about this hernia have been reported. After increased incidence of operations for morbid obesity, reports on retroanstomotic hernia have increased.