INTRODUCTION Duodenal ulcer penetration into the liver is a rare, but serious complication. Its frequency was thought to have decreased owing to advances in therapies for peptic ulcers. However, we encountered a case in which the duodenal ulcer had penetrated into a previous hemihepatectomy site. PRESENTATION OF CASE A 69-year-old man with a history of left hemihepatectomy 20 months previously presented to the emergency room with sudden-onset abdominal pain and nausea. An upper gastrointestinal examination with a fiberscope revealed a giant ulcer in the duodenal bulb. In addition, a foreign body was detected at the ulcer floor and was strongly suspected of being a ligature from previous hemihepatectomy. DISCUSSION The presence of a gas-filled liver mass and bowel wall thickening with inflammatory changes are important imaging findings for prompt diagnosis of such a condition, but in this case, none of these were reported. Further, no definite abscess was found. Thus, the patient was treated conservatively with a proton pump inhibitor. CONCLUSION This case demonstrates the importance of using absorbable suture materials, adequate lavage in the postoperative peritoneal space and gastroduodenal mucosal protection postoperatively.