The new information, that has become available at present, makes it possible to outline a mechanism of brain water metabolism in the realization of which an important role belongs to AQP4, the main aquaporin of the brain. This aquaporin controls water transfer across the blood-brain barrier and water exchange between brain parenchyma and the cerebrospinal fluid. In the world literature, AQP4 is viewed as a molecular target for the drug action directed at correction of the brain water metabolism disorders in pathologies. The new knowledge made it possible to outline principal approaches to pharmacological correction of cerebral water metabolism disorders and edema.