Mucoceles of the paranasal sinuses are benign, expansile, and locally destructive lesions that are thought to occur secondarily to obstrution of the sinus otsia. Frontal sinus is the most common site for the primary mucoceles of the paranasal sinuses. Operative management of frontal sinus mucoceles include ablation, obliteration, and drainage. This paper presents 9 cases of frontal sinus mucoceles operated in Asan Medical Center between July 1992 and August 1995. The age range of patients was between forties and seventies and male to female ratio was 5 : 4. Underlying factors were chronic paranasal sinusitis(7 cases), previous sinonasal surgery(4 cases), and trauma(2 cases). Postoperative follow-up period was between 1 month and 22 months. Five cases were treated via extranasal and four cases via intranasal approach. Obliteration was done in 2 cases, and drainage operation in 7 cases including 3 cases of endoscopic marsupialization. Intranasal approaches, especially endoscopic marsupialization, appeared to have more advantages including low morbidity, relatively short operation time and hospitalization day, and minimal sequelaes or complications. However endoscopic marsupialization needs meticulous endoscopic techique, and intimate knowledge of the anatomy, patients' compliance, and periodic postoperative follow-up.