1) The variation of the brain water content caused by the acute venous and arterial bleeding from the upper sagittal sinus and the common carotid artery and by acute cerebral congestion after ligation of the internal jugular vein was estimated in each part of the cerebral cortex, white substance, brain stem and cerebellum. The free, bound and total water of the brain were measured directly after the operation and then 10 minutes, 1, 3 and 6 hours after the opeartion, using Hatschek's cobaltchloride method. 2) There was seen a maximal increase of the free and total water in every parts since the time of acute venous bleeding, and it tended to decrease as time elapsed. 3) The free and total water content in every part increased since the opeartion of acute arterial bleeding, but it reached to the maximal after 60 minutes and then fixed. 4) The free and total water content increased directly after the acute brain congestion and increased with the time gradually. 5) The increase of the brain water content always depended upon the free water, and no increase of the bound water was seen; namely we found always the edematous type. 6) The quantitative variation of brain water content with the time in cases of arterial and venous bleeding and congestion was identified by the difference of each mechanism of brain edema. It seemed that there was no essential qualitative difference of the completed state of brain edema. 7) The brain water content increased more distinctly in the white matter and the brain stem than the cerebral cortex and the cerebellum.