Abstract Background Splenic artery aneurysms usually rupture into the free peritoneal space and rarely into the gastrointestinal tract. We report the case of a patient with a giant splenic artery aneurysm that ruptured in to the stomach with hemorrhagic shock and was successfully treated with emergency surgery. Case presentation A 59-year-old man presented to the emergency department with chest pain and syncope. Contrast-enhanced computed tomography showed splenic artery aneurysm with active contrast extravasation. He developed upper gastrointestinal (UGI) bleeding and hypovolemic shock. We diagnosed a splenic artery aneurysm ruptured in to the stomach, performed emergency distal splenopancreatectomy including the aneurysm and partial gastric resection, and could prevent patient death. Conclusions This report shows that splenic artery aneurysm can cause UGI bleeding. Thus, clinicians should be alert about this condition when managing patients with UGI bleeding and/or splenic artery aneurysm.