Despite the availability of new broad-spectrum antibiotics, sinusitis occasionally causes significant morbidity and mortality. One serious complication of paranasal sinusitis is subdural empyema, a fulminating intracranial disease that is invariably fatal if not treated. The symptoms of subdural empyema may be mild and may be the same as those associated with sinusitis, or the infection may result in alteration of the level of consciousness and focal neurologic deficits. Rapid recognition and treatment of subdural empyema is extremely important. Before magnetic resonance imaging became available, computed tomography was used for rapid diagnosis of this infection. Magnetic resonance imaging, however, is now becoming the diagnostic tool of choice. Neurosurgical intervention and high doses of intravenously administered antibiotics are the mainstays of treatment. If treatment is initiated as soon as the diagnosis of subdural empyema is made, the patient has a good chance of recovering with no, or only slight, neurologic defects.