BACKGROUND Endovascular embolization has been used to control gastrointestinal tumor bleeding. Lots of embolic agents have been applied in embolization, but liquid embolic materials such as Onyx have been rarely used because of concerns about severe ischemic complications. OBJECTIVE To evaluate the clinical efficacy and safety of transcatheter arterial embolization (TAE) with Onyx for acute gastrointestinal tumor hemorrhage. METHODS Between September 2011 and July 2013, nine patients were diagnosed as acute gastrointestinal tumor hemorrhage by clinical feature and imaging examination. The angiographic findings were extravasation of contrast media in the five patients. The site of hemorrhage included upper gastrointestinal bleeding in seven cases and lower gastrointestinal bleeding in two cases. TAE was performed using Onyx in all the patients, and the blood pressure and heart rate were monitored, the angiographic and clinical success rate, recurrent bleeding rate, procedure related complications and clinical outcomes were evaluated after therapy. The clinical parameters and embolization data were studied retrospectively. RESULTS All the patients (100%) who underwent TAE with Onyx achieved complete hemostasis without rebleeding and the patients were discharged after clinical improvement without a second surgery. No one of the patients expired during the hospital course. All the patients were discharged after clinical improvement without a second surgery. Postembolization bowel ischemia or necrosis was not observed in any of the patients who received TAE with Onyx. CONCLUSIONS TAE with Onyx is a highly effective and safe treatment modality for acute gastrointestinal tumor hemorrhage, even with pre-existing coagulopathy.