We report the case of a 65 year old female patient with biopsy-proven cerebral amyloid angiopathy (CAA). She experienced intracerebral hemorrhages 4 times during 23 days but these serious strokes did not recur after corticosteroid therapy was started and her condition greatly improved. Since high titers of antinuclear antibodies and elevated erythrocyte sedimentation rate were found in her serum, she may have an inflammatory disorder involving amyloid-laden cerebral vessels. This is the first report showing the usefulness ofcorticosteroid for the treatment of CAA-related cerebral hemorrhages. Additionally, the concentrations of Abeta40 and Abeta42 in the CSF of this patient decreased rapidly after the use of corticosteroid, and ultimately fell far below normal values.