The authors performed clinical-pathologic correlation to assess the validity of the Boston diagnostic criteria for cerebral amyloid angiopathy (CAA). Thirteen subjects were diagnosed clinically with probable CAA from among 39 patients with available pathologic tissue in a prospective cohort of subjects aged > or = 55 years with primary lobar hemorrhage. All 13 individuals were confirmed neuropathologically as having CAA. This small pathologic series indicates that the diagnosis of probable CAA can be made during life with high accuracy.