Gastrointestinal ulcers occur frequently and are mainly caused by H pylori infection. In this report, we present a rare case of gastro-duodenal ulcer following selective internal radiation therapy (SIRT). SIRT is a palliative treatment for unresectable liver tumours. During SIRT, 90Y-microspheres are infused into the hepatic artery. Pre- treatment evaluation for the presence of arterial shunts to neighbouring organs should be determined in order to avoid complications of SIRT. Gastrointestinal ulcers occur frequently and are mainly caused by H pylori infection. In this report, we present a rare case of gastro-duodenal ulcer following selective internal radiation therapy (SIRT). SIRT is a palliative treatment for unresectable liver tumors. During SIRT, 90Y -microspheres are infused into the hepatic artery. Pre-treatment evaluation for the presence of arterial shunts to neighbor organs should be determined in order to avoid complications of SIRT.