&NA;Cerebral edema remains a major clinical problem despite intense investigation and multiple therapeutic interventions. In this review the author summarizes the major issues involved and the current experimental and clinical work being done in the areas of etiology, mechanisms, and treatment. Emphasis is placed on the importance of the blood‐brain barrier, astroglial compartmentalization of ions, energy considerations, the relationship of cerebral edema to increased intracranial pressure, and resolution of the process. Current treatment modalities and their efficacy are discussed in terms of our present knowledge of the issues involved.