Epistaxis is a frequent health problem and the most common cause of emergency in otorhinolaryngology practice. In this report, a case of a 26-year-old patient with intractable epistaxis after endoscopic sinus surgery was presented. The epistaxis began at the fourth postoperative day and was unresponsive to endoscopic cauterization and anterior and posterior nasal packing. On angiographic investigation, a pseudoaneurysm of the sphenopalatine artery was detected and treated with microcatheter embolization. This is the second case of postoperative sphenopalatine pseudoaneurysm as a complication of endoscopic sinus surgery in the literature.