Gastrojejunocolic fistula is a rare condition after gastrojejunostomy. It is severe complications of gastrojejunostomy, which results an inadequate resection or incomplete vagotomy during peptic ulcer surgery. The symptoms are diarrhea, upper abdominal pain, bleeding, vomiting and weight loss. A 55-year-old man with chronic diarrhea and weight loss for 6 months visited Dankook University Hospital. The patient had received a truncal vagotomy and gastrojejunostomy for duodenal ulcer obstruction 15 years previously. The patient underwent gastroscopy and upper gastrointestinal series evaluations, which detected the gastrojejunocolic fistula. After improving of malnutrition, an exploratory laparotomy was undertaken, which revealed that the gastrojejunostomy site and the T-colon formed adhesion and fistula. En block resection of the distal stomach and T-colon included the gastrojejunocolic fistula, and Roux-en-Y gastrojejunostomy was performed. Recovery was uneventful and the patient remained well at the follow-up. We report a gastrojejunocolic fistula, which is a rare case after gastrojejunostomy.