Primary angiitis of the central nervous system has until recently been considered rare, usually progressive, and untreatable. In 1987, preliminary diagnostic criteria for the disorder were proposed in the hope of gaining a more accurate description of the disease. We used these criteria in reviewing all cases reported in the English language (99 cases) and those seen at The Cleveland Clinic Foundation (9 cases). We believe that the disorder is heterogeneous, and has a better prognosis than previously thought. Furthermore, a relatively benign subset of this disorder, termed "benign angiopathy of the central nervous system," can be defined on clinical grounds. We propose a revised set of diagnostic criteria and a practical approach to treatment.