An increase in pressure of the venous outflow under conditions of perfusion with constant blood flow of hemodynamically isolated brain, led to filtration of fluid from the cerebral vascular bed in anesthetized cats. Velocity of the transvascular translocation of fluid was proportional to the pressure increase by 50, 75 and 100 mm Hg in cerebral veins. The capillary filtration coefficient (CFC) was about 0.11-0.12 ml/100 g of tissue/mm Hg/min. Reasons for a relatively great CFC found in the brain, are discussed.