Systemic lupus erythematosus (SLE) is a relapsing-remitting autoimmune disease with CNS involvement occurring in up to 75% of patients. However, the frequency of neuropsychiatric manifestations in SLE studies varies widely, depending on the type of manifestations included and the method used for evaluation. CNS involvement may be considered primary if directly related to SLE activity in the CNS or secondary when related to treatment, infections, metabolic abnormalities or other systemic manifestations such as uraemia and hypertension. The pathogenesis of neuropsychiatric SLE is as yet unknown, though numerous autoantibodies and cytokines have been suggested as possible mediators. However, independent of the aetiology of the insult, the final common pathway in neuropsychiatric SLE is the involvement of the cerebral microvasculature. The diagnosis of primary CNS involvement by SLE is often difficult, as both focal and diffuse manifestations may occur and there is no gold standard for diagnosis. A high index of clinical suspicion, in addition to laboratory and neuroimaging findings may support the diagnosis. Treatment is mostly empirical, although one randomized controlled trial has shown that cyclophosphamide in addition to methylprednisolone is superior to methylprednisolone alone in severe neuropsychiatric SLE.