Suppurative complications of sinusitis usually result from the extension of the suppurative process from the affected sinus to adjacent areas such as soft tissues, orbits, frontal bones and intracranial spaces. Intracranial spread and cause meningitis, encephalitis, extradural & subdural abscesses and brain abscess. Pathogenesis of intracranial complications was through the bony defect or hematogenous. After introduction of CT scan, the diagnosis and treatment improved. And as the significance of anaerobe was proved, the appropriate antibiotic therapy becomes more effective. Recently we have experienced one extradural abscess and one frontal encephalitis secondary to acute ethmoiditis.