BACKGROUND Cerebral amyloid angiopathy is considered pathogenic in non traumatic cerebral lobar hemorrhages. OBJECTIVE To study the frequency of cerebral amyloid angiopathy in brains of patients dying of non traumatic cerebral hemorrhages. METHODS Thirty seven brains from patients, 25 men and aged 65 +/- 10 years old, with cerebral hemorrhages (14 lobar, 18 in basal ganglia and 5 in cerebellum or brainstem) were studied. As controls, the brains of 30 subjects, 14 men and aged 64 +/- 16 years old, dying of non neurological causes were studied. Deep and cortical vessels were stained with hematoxylin eosin, Gomori, Thioflavin T and Bodian. Definitive cerebral amyloid angiopathy was diagnosed when amyloid deposition was observed in the media of vessels. RESULTS Twenty six out of 32 patients dying of cerebral hemorrhage and 3 of 21 controls had chronic hypertension. Cerebral amyloid angiopathy was present in 19 of 37 brains of patients with cerebral hemorrhage and 13 of 30 control brains. In patients with hypertension, vascular changes independent of the location and volume of amyloid deposition, were observed. Such changes were dilatation, tortuousness, thickening of walls specially in muscular and adventitia and hyaline degeneration. Thirteen brains with hemorrhage had fibrinoid necrosis and 10 had microaneurysms. CONCLUSIONS In this series of patients, cerebral amyloid deposition was unspecific and its role in the pathogenesis of cerebral hemorrhages was not confirmed. Hypertension was associated with vascular degenerative changes that can lead to cerebral hemorrhages.