Sixteen patients (8 female, 8 male) with primary angiitis of the CNS (PACNS), were followed prospectively in a vasculitis clinic. Diagnosis was by angiography in patients without underlying disease. Median age at diagnosis was 36.5 years, and median duration of follow-up was 28 months. Onset was acute in 14 patients (88%), with 3.5 weeks (median) from onset symptoms to diagnosis. Three women developed symptoms within 3 weeks postpartum. The most frequent symptoms were severe headaches (12, 75%), stroke (6, 30%), transient ischaemic attack (TIA) (4, 28%), seizures (7, 44%), visual aberration (3, 19%), and cognitive impairment (5, 31%). Laboratory data included high ESR (2, 13%), leucocytosis (8, 80%), thrombocytosis (1, 6%), positive antinuclear antibody titre (3, 15%), and high levels of complement (5, 31%). Lumbar puncture was performed in 12 patients (75%). CSF analysis was abnormal in five patients (42%). EEG was abnormal in 5/9 patients. The major CT/MRI scan findings were cerebral haemorrhage (4, 25%), brain infarcts (5, 31%), brain atrophy (2, 13%) and non-specific lesions (2, 13%). Four patients had normal studies. All patients received corticosteroids (CS), and five were treated with oral cyclophosphamide. Two patients relapsed despite CS and cyclophosphamide therapy. All patients are alive, and at the last assessment, eight had a permanent neurological deficit, which included paresis (3, 19%), neurocognitive abnormalities (2, 13%), visual loss (2, 13%) and seizure activity (5, 31%). Our data suggest a non-progressive, non-fatal course in those PACNS patients diagnosed angiographically and treated with CS with or without cyclophosphamide.