Epistaxis from the posterior superior region of the nasal cavity might be fatal in some cases. It is particularly severe in an individual with hypertension, arterial aneurysm of traumatic origin, and bleeding from posterior lateral nasal artery, which is frequently difficult to reach and ligate directly on a bleeding area. Certain cases have been reported in which the bleeding could be stopped only by ligating/embolization of the external carotid artery or the internal maxillary artery at its branching off from the external carotid artery. Despite the multiple anastomoses, the effect of such ligation or cauterization is effective if properly done. We present a case of a 25-year-old young man with a 3-month history of recurrent epistaxis resulting from an internal maxillary artery aneurysm following trauma. The clinical presentation, diagnosis, and successful endoscopy treatment of posterior epistaxis are presented.