Systemic lupus erythematosus (SLE) is an inflammatory disease in which up to two thirds of the patients present neurological symptoms. The diagnosis of the disease is based on clinical findings and the presence of autoantibodies, and the pathogenesis is unclear. The purpose of this study was to determine if the pathogenesis was partly mediated via nitric oxide (NO) formation. Cerebrospinal fluid (CSF) samples from 15 patients with cerebral SLE were analyzed for the NO metabolites nitrite and nitrate using capillary electrophoresis. The severity of neurological symptoms was scored by dividing the patients into two groups with either mild or moderate/severe CNS involvement. All patients with cerebral SLE showed increased levels of NO metabolites. In CSF, there was a relationship between signs of NO production and clinical results showing that increased levels of nitrite and nitrate were associated with more severe neurological symptoms. These findings may shed new light on the pathogenesis of cerebral SLE, and analysis of nitrate and nitrate may prove to be of value in monitoring the activity of the disease.