Systemic lupus erythematosus is a chronic inflammatory disease of unknown origin which can affect nearly every organ system. Young women are involved more frequently than men. SLE is characterized by periods of remissions and chronic or acute relapses. Diagnosis of SLE requires the presence of typical clinical and immunological criteria. Patients suffer from a wide array of symptoms and have a variable prognosis depending upon the severity and the type of organ involvement. Effective treatment is based on accurate determination of disease activity by clinical investigation, evaluation of characteristic autoantibodies like anti-DNA antibodies and determination of organ function with focus on renal and cerebral manifestations. The goal of treatment is stable remission which can be reached using immunosuppressive drugs like corticosteroids, antimalaries, azathioprine or cyclophosphamide. Longterm success requires avoidance of corticosteroid-induced toxicity, infections and accelerated atherosclerosis.