Systemic lupus erythematosus (SLE) is a chronic, multisystem, autoimmune disease in which neuropsychiatric involvement occurs in about 50% of patients and carries a poor prognosis. Despite extensive research, the precise mechanisms of nervous tissue injury remain the least well understood. This article summarizes the important clinical neuropsychiatric features of SLE and, reviewing classical histopathological and more recent experimental studies, discusses theories concerning their presumed pathogenesis. The distinctive production of diverse autoantibodies seems to be related to defective clearance of apoptotic cells. Antibody-mediated neural cell injury and rheological disturbances represent the two principal suggested mechanisms of tissue injury. An interplay between these processes, underlying genetic factors, their modification by hormones, complicated by a number of secondary factors, may explain the wide spectrum of features encountered in this disease.