Frontal Mucocele grows gradually and unnoticed as a benign lesion but, as the frontal mucocele expands to and compresses surrounding organs like brain, orbit, etc., it can cause diverse symptoms and signs. Although the surgical approaches of mucocele include open, endoscopic and combined approach, endoscopic marsupialization has been commonly used because endoscopic marsupialization was reported with high success rates, low complication rates and better operative vision. However, recently we experienced rare complication of endoscopic marsupialization of huge frontal mucocele, large amount of intracerebral hemorrhage, immediately after successful surgery and report this rare case with short review.