The present study is a clinical and pathological analysis of 135 cases of spontaneous massive cerebral hemorrhage in which hemodynamic disorders, especially hypertension, constitute the significant etiologic factors. Massive cerebral hemorrhage is defined as those lesions at least 3 cm in largest dimension in the cerebral hemispheres or 1.5 cm in the brain stem, thus coinciding with Russell's definition.12Hemorrhages associated with injury, blood dyscrasias, and malformations have not been included in the basic study. Origins of Hemorrhage.— The hypertensive group formed 60% of a total of 225 autopsy proven, nontraumatic cerebral hemorrhages. Cerebral aneurysm was responsible for 20% and blood dyscrasias for 13%. The various conditions found in the present group of hemorrhages are shown in Table 1. Clinical Features Onset of the Strokes.— The onset of cerebral hemorrhage is usually sudden but may be gradual under special circumstances. In two thirds of the cases in this series