1. After brain damage experimentally induced by balloon compression, liquor of the cistern shows a metabolic acidosis with significantly increased lactate level and L/P quotient, and statistically distinct decrease of pH, oxygen tension, and bicarbonate level. 2. There is a considerable disproportion between the changes of acid-base metabolism, gas tension, and metabolic products in cerebrospinal fluid compared with much less expressed disturbances in the blood. 3. The advanced edematous phase shows distinct accumulation of water in the tissue, considerable increase of intracranial pressure, resp. decrease of effective perfusing pressure, loss of autoregulation, and decreased regional and global cerebral circulation, while the pathologic alterations of cerebral fluid are intensified. 4. Treatment of lactate acidosis in the liquor by intrathecal application of sodium bicarbonate results in improved cerebral circulation and metabolism of the cerebral tissue, having thus a good influence on cerebral damage and its sequels.