Patients (37) with head injury and radiographic or tomographic signs of fracture of the skull involving the anterior and/or middle fossae were examined by metrizamide CT (computed tomography) cisternography (MCC). Patients (24) presented with clinical evidence of osteo-meningeal breach (CSF rhinorrhea, purulent meningitis). The breach was accurately located in 16. In the remaining 13 patients the MCC examination gave negative results. While this method is useful to pinpoint a clinically overt breach, especially in patients with multiple fractures, it does not seem to help in discovering asymptomatic breaches.