Endoscopic surgery of frontoethmoidal mucocele affords the potential clinical significance for reducing operative morbidity of surgery because of minimal operation time and its bleeding. Following surgery, direct endoscopic visualization of the area enables accurate follow-up. Unlike sinus obliteration, the ability to accurately image the sinus by CT scan is also preserved. Recently, we experienced and followed a case of frontoethmoidal pyocele for 6 months, which extended into the intracranium, and was satisfactorily treated endoscopically. The clinical implication of the results need more sustained follow up and to be compared with other surgery. The purpose of this report is to share our experience for perfoming an endoscopic intranasal surgery of frontoethmoidal mucocele.