Cerebral vasculitis is a serious but uncommon condition which presents considerable difficulties in recognition, diagnosis and treatment. We studied eight consecutive patients in whom this diagnosis was made. Despite the great diversity of symptoms and signs, we noted three clinical patterns: (i) acute or sub-acute encephalopathy, (ii) a picture with some similarities to multiple sclerosis (‘MS-plus’), and (iii) features of a rapidly progressive space-occupying lesion. The identification of these patterns may help recognition of cerebral vasculitis. The diagnostic value of four investigative procedures not previously studied in cerebral vasculitis was assessed: ophthalmological examination using low-dose fluorescein angiography with slit-lamp video microscopy of the anterior segment (abnormal in 4/5 patients); spinal fluid oligoclonal band analysis (abnormal in 3/6 patients); anti-neutrophil cyto-plasmic antibody assay (abnormal in 3/8 patients); and indium-labelled white-cell cerebral imaging (positive in only one patient). Treatment was with steroid alone (n = 2) or steroid with cyclophosphamide (n = 6). Seven patients responded clinically.