Author reports a case of foreign body of the frontal sinus. The patient was a 37-year-old Korean man. He complained recurrent diffuse swelling with tenderness at the region of the left frontal sinus ever since an operation for intracranial aneurysm. Osteoplastic technic was applied for exploration of the frontal sinus and found that the sinus was being filled of bone wax which had entered through a drill hole. After complete removal of the foreign body and diseased sinus mucosa, obliteration of the sinus cavity with autogenic abdominal fat was carried out. And an excellent result obtained.