The pattern of morphological changes in blood clots, brain tissue and vessels of hypertensive hematomas (CH) was studied in 79 surgical and autopsy cases. Brain tissue compression degeneration of cells and fibers, edema were observed during the first 6 hours after the onset of hemorrhage. Necrosis and marked leukocyte infiltration appeared to progress gradually and reach maximum by the disease day 2-3. The degeneration manifested by formation of gliomesodermal capsule surrounding the haemorrhagic lesion from day 3 to 8. Dilatation of small cerebral vessels was followed by an increase in permeability and necrosis of vascular walls predominated within 24-72 hours after initial bleeding. It is suggested that the first 24 hours after CH onset are optimal for surgery.