This is a review of 80 cases of intracranial meningiomas, which were operated on in the neurosurgical Service of Lausanne. 51 tumors were associated with an area of low attenuation of variable extension on the CT-scan. In 49 of these, the low attenuation areas corresponded to oedema. In two of them a cyst was discovered at operation. One was a subarachnoid cyst and the other one was an intracerebral cyst separated from the tumor by a thin layer of cerebral cortex. A correlation was attempted between these areas of low attenuation and the clinical history, the CT-scan characteristics, the location, the macroscopic appearance at operation and the histology of the tumors. From these data, the typical features of a meningioma more likely to be associated with an area of low attenuation on the CT-scan were determined. This tumor is often located in the subfrontal area or in the middle base of the skull, and epilepsy or increased intracranial pressure are more likely to be present. The most common histological type is syncytial.