Systemic lupus erythematosus (SLE) is a prototypic multisystem autoimmune disease with a vast spectrum of clinical presentations including almost all body organs and tissues. The incidence of lupus has tripled in the last 40 years, mainly due to the improved diagnosis. For more than 60 years the presence of autoantibodies in patients with SLE has been known. A great effort is being made for understanding the diagnostic, pathogenic and prognostic meaning of these autoantibodies. The study demonstrated the significance of autoantibodies test in Egyptian SLE patients. The results showed that 93.3% of patients have positive ANA test, 90% have positive anti-dsDNA. Anti-Sm antibodies were in 40% and 49.3% of patients have positive anti-nucleosome antibody test. Also, 30.6% of patients deve-loped a positive anti-histone test & 26% have positive anti-ribosomal test. Anti-phospholipids antibodies were found in 44.6% of patients. Levels of C3 & C4 (0.552±0.43 & 0.125±0.12, respectively) were lower than that of control group (1.2±0.35 & 0.42±0.54 for C3 & C4, respectively).