The most frequent complication of an acute cerebral lesion is brain edema. With increasing size of brain edema an increase in intracranial pressure is observed. This leads to decreased cerebral perfusion and brain death. Cerebral edema can be subdivided into three groups: vasogenic, cytotoxic and interstitial brain edema. This classification is of relative importance because only the extracellular edema can be influenced by drugs. Clinical symptoms of brain edema are related to the increased intracranial pressure, associated with decreased cerebral microperfusion. Symptoms are headache, vomiting, vision disturbances and, with increased intracranial pressure, bradicardy, respiration disturbances and at the end brain death by compression of the cerebrum. Therapy is directed to the underlying disease. Unfortunately, even today specific therapeutical approaches are limited.