We report a case of extensive left gastric artery collaterals that were formed in the region of gastric fundus due to splenic artery occlusion and resulted in massive hematemesis. These collaterals were thought to be portosystemic collaterals related to portal hypertension during upper endoscopy study and single-phase venous computed tomography studies. The collaterals were treated by transcatheter endovascular coil embolization. Our case highlights the importance of recognizing and differentiating left gastric artery collaterals from gastric venous varices as a cause of hematemesis since the treatment approach for each condition is totally different. It also introduces the feasibility of percutaneous left gastric artery embolization as a treatment for this condition, without the need for surgical splenectomy and partial gastrectomy which have a higher mortality and morbidity. © The Author(s) 2012.