A retrospective study of cerebral edema in 40 patients with intracranial meningiomas seems to demonstrate that the extent of edema is not related to anatomical factors such as location. Histological type is more significant; cerebral edema is usually observed with meningothelial forms. Furthermore, the study of tumor cells by electron microscopic methods indicates that secretory-excretory activity is closely associated with with the production of peritumoral edema. The ultrastructural aspects of this secreted material are described, but further biochemical studies are necessary to determine its exact nature. The possible role of tumoral steroid receptors in the secretory-excretory phenomenon is discussed.