Seventy-one patients with systemic lupus erythematosus and clinical evidence of nephritis were seen during a 15-year period, and followed for a mean of seven years. Survival was calculated to be 76 per cent at five years and 57 per cent at ten years from onset of clinical nephritis; and 80, 65, 55 and 55 per cent five, ten, fifteen and twenty years from onset of clinical lupus. Renal biopsies showed mild or focal lesions in 30 per cent of patients, membranous lesions in 14 per cent and diffuse proliferative lesions in 55 per cent. However, there was no difference in the long-term outcome of the different histological groups. Nineteen patients (27 per cent) died during follow up, eleven from renal failure, six from sepsis and two from cerebral lupus. Death in renal failure is now usually a late event in lupus, even in patients with clinical evidence of severe nephritis. The prognosis of even severe lupus nephritis is now better than formerly reported. Reducing the dose of corticosteroid drugs, by the use of cytotoxic drugs such as azathioprine may have diminished the mortality from cardiovascular complications. Side effects of treatment, however, remain an important cause of death and morbidity.