Inflammatory cerebral amyloid angiopathy (CAA) typically affects older patients who present with acute or subacute cognitive decline, headache, behavioral change, seizures, and focal neurological deficits. Brain magnetic resonance imaging (MRI) reveals patchy or confluent asymmetric white matter hyperintensities on T2-weighted or fluid-attenuated inversion recovery images, which indicates vasogenic edema, and previous lobar hemorrhages and/or multiple lobar microbleeds on T2*-weighted gradient-recalled echo or susceptibility-weighted imaging. Neuropathological findings include frank vasculitis and/or perivascular inflammation with mononuclear or multinucleated giant cells that are associated with amyloid-beta (Aβ)-laden vessels. Importantly, these findings suggest that these patients may respond well to immunosuppressive treatment with high-dose corticosteroids and/or cyclophosphamide. The pathogenesis of this syndrome is still unknown, although anti-Aβ autoantibodies in the cerebrospinal fluid may mediate inflammatory processes against cerebrovascular Aβ. Moreover, MRI findings in patients with inflammatory CAA are very similar to those in patients with Alzheimer's disease who were treated with a monoclonal anti-Aβ antibody, and these findings are called amyloid-related imaging abnormalities (ARIA). Anti-Aβ autoantibodies in the cerebrospinal fluid might be a biomarker of future disease-modifying therapies for patients with Alzheimer's disease and CAA.