Cases showing complications such as esophageal injury, deep neck infection, and mediastinitis caused by accidental ingestion of fish bone are common. But ingestion of fish bone rarely causes perforation of the gastrointestinal tract or an intra-abdominal abscess.

We report herein a case of a 78-year-old man with a periumbilical mesenteric abscess caused by fish bone which was ingested unconsciously. The fish bone was found in the terminal ileum and it was removed by colonoscopy. The patient improved and he was discharged after systemic antibiotic therapy. Occasionally, when patients swallow fish bone without a foreign body sensation, clinicians should suspect perforation caused by fish bone in case of an intra-abdominal abscess of unknown cause.