Selecting the least invasive operation likely to eraidcate an obstructing focus is the ideal surgical management of frontal sinus disease. Frontal sinus surgery has consisted of abkaton, obliteration and reconstruction of ansofrontal drainage, which are performed via external approah under general anasthesia. Although providing excellent frontal exposure, frotal osteoplasty addreddes less about nasofrotal draunage and its morbidity has precluded unform acceptance. Ostioplasty is a procedure to open the frontal sinus ostium or isthmus for frontal deatinage and ventilation. Functional endoscopic sinus surgery offers a minimally invasive approach for frontal ostioplasty and reduced morbidity for procedure performed under local anesthesia. It is a revolutionary procedure which is not only corresponding with the concept of frontl mucociliary clearance function but also fulfilling endonasal approach for froontal siuus drainage. This paper presents our preliminary experience of functional endoscopic frontal sinus surgery with consecutive scaes of frontal sinus diseaes which visitsd this department in 1991. Even thogh some cases post-poeratively show partial ocnstriction of frontal isthms, their drainage and ventilation appar to be patent and the preliminary result is encouraging. We report the operative methods and the cases.