Diffuse fusiform intracranial aneurysms have been reported in children with human immunodeficiency virus (HIV) for over 2 decades, but have only recently been reported in adults with HIV. Although these aneurysms have important clinical implications, their etiology and optimal therapy are unknown. We present a systematic review of diffuse intracranial fusiform aneurysmal vasculopathy in patients who are HIV-positive. We conducted a comprehensive literature search for relevant case reports and reviews published before February 2009. Patients were included if they had HIV infection and radiographic imaging consistent with fusiform aneurysmal vasculopathy. We identify 11 published adult cases of intracranial fusiform aneurysmal vasculopathy and describe 1 unpublished case from our own institution. Available data regarding clinical presentation, characteristic imaging findings, and treatment of this complex syndrome are reviewed. Adults with HIV-associated intracranial aneurysmal vasculopathy typically are significantly immunosuppressed and present with gross neurologic dysfunction. Characteristic radiographic findings include diffuse cerebral fusiform aneurysms with hemorrhage or infarct. Treatment of any active infection followed by the initiation of antiretroviral therapy and corticosteroids may be a reasonable approach in this complex syndrome.