We investigated incidence, age distribution in relation to etiology, and localization of spontaneous intracerebral hematoma in 100 consecutive cases. Incidence in the total population of the Giessen area was estimated to be greater than 11/100,000 inhabitants/yr and increased with age. There was a trend toward higher incidence in males. Overall mortality was 27%, 22% of 58 patients aged less than 70 years and 33% of 42 patients aged greater than or equal to 70 years. Hypertensive putaminal hematoma showed the highest mortality rate (42%, 10 of 24 cases). Chronic alcoholism and anticoagulant medication influenced the mortality rate unfavourably. We found the following localizations and etiologies to have a specific relation with age: 1) lobar hematomas from vascular malformations, group aged less than 40 years; 2) hypertensive putaminal hematomas and hypertensive thalamic hematomas, group aged 40-69 years; and 3) lobar hematomas, group aged greater than or equal to 70 years. Alcoholism was an additional factor in 38% of the 13 middle-aged men with hypertensive putaminal hematomas. Fourteen cases of spontaneous intracerebral hematoma were possibly due to cerebral amyloid angiopathy. Six of these 14 patients had recurrent lobar hematomas, but only three of the six could be histologically investigated. In these three cases, cerebral amyloid angiopathy was proven.