Intracranial hypertension and brain hydration were scrutinized during acute ethanolism for consideration in the combined head injury setting. Intraventricular pressures and whole brain water levels rose with moderate or high ethanol dosages. The most prominent alterations were associated with respiratory acidosis and hypoxia; less marked changes were found in their absence and point to a second mechanism. Elevated central venous pressures appeared as well in some instances to constitute a third action. It is accordingly suggested that ethanol may add significantly to the combined pathology with associated acute head injury in several ways. These include: contributions to edema formation, to respiratory depression, and to alterations in local hemodyamics.