A case of an intracerebral aerocele as a complication of an osteoma in the frontal sinus is reported. The patient had been investigated 7 years earlier for three episodes of idiopathic nocturnal epilepsy. Roentgenograms of the skull at that time showed the presence of a small osteoma within the frontal sinus. Removal of the osteoma was undertaken via a bifrontal approach and repair to the dural defect was made with a temporalis fascia graft. Postoperatively, the patient made a good recovery but developed frequent focal left hemisphere epilepsy. It is our view that sinus osteomas that are incidentally found should be removed before complications arise.