Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the production of autoantibodies to components of the cell nucleus with diverse clinical manifestations, predominantly in women during reproductive years. SLE is caused by interaction between susceptibility genes and environmental factors, which result in abnormal immune response. SLE is caused by failure in regulating the production of pathogenic autoantibodies and the formation of immune complex. Abnormalities in the immune response regulation display a decreased ability to clear immune complexes and apoptotic cells. Genetic predisposition to SLE involves multiple genes. Genetic variants predisposing to SLE may influence clearance of immune complexes or apoptotic bodies, activation of B cells or T cells, and inflammation related to dendritic cell activation. Environmental factors that predispose to or activate SLE include ultraviolet B light, infection with Epstein-Barr virus, female gender, and exposure to estrogen-containing medications. The diagnosis of SLE is based on characteristic clinical features and autoantibodies. The diagnostic criteria of the American College of Rheumatology (ACR) reflect the major clinical features of the disease (mucocutaneous, articular, serosal, renal, neurologic) and incorporate the associated laboratory findings (hematologic and immunologic). Four or more criteria are required for diagnosis. There is no effective cure for SLE, and complete sustained remissions are rare. The treatment should be tailored based on the clinical manifestations in an individual patient. Conservative therapies for management of non-life-threatening manifestations of SLE comprise NSAIDs, corticosteroids and antimalarials. Treatment of severe organ damage requires immunosuppressive agents. Targeted biologic therapies are under development and appear to be promising.