The most usual form of cerebral amyloid angiopathy is due to deposition of B protein on vessel walls. This senile angiopathy is often, but inconstantly, associated with Alzheimer's disease, and rarely causes intracerebral hemorrhage, which is typically lobar and recurrent, occurring in elderly normotensive patients with ou without dementia. There is probably no cause-effect relationship between senile cerebral amyloid angiopathy and Alzheimer's disease, which may occur independently and seems to represent two modalities of cerebral amyloidosis. Other forms of cerebral amyloid angiopathy are exceptional: hereditary cerebral hemorrhages with amyloidosis differ from each another in type of fibrillar protein (cystatine-C, variant of B protein, transthyretine).