Abstract: Systemic Lupus Erythematosus (SLE) is not a rare disease in Iran. In the past 13 years, we have seen 503 cases, with the following characteristics. Females 87%, males 13%, mean age 23 years (SD=11.25). Clinical manifestations were as follow: General manifestation in 57% (fever 52%, fatigue 39%, lack of appetite 18%, weight loss 36%). Mucocutaneous manifestations in 80% (malar rash 67%, discoid lesions 9%, photosensitivity 45%, alopecia 9%, Raynaud's phenomenon 11%, oral ulcers 35%). Osteoarticular Manifestations in 79% (Arthralgia 57%, acute arthritis 15%, sub acute and chronic arthritis 41%, Erosive arthritis with deformity 3%, myositis 4%). Renal Manifestations in 67% (proteinuria 67%, hematuria 38%, leucocyturia 29%, casts 27%). Neurologic Manifestations in 15% (convulsion 10%, psychosis 6%, central manifestations 3%, peripheral manifestations 2%). Cardiac manifestations in 10% (pericarditis 6%, myocarditis 2%, failure 2%). Pleuropulmonary manifestations in 23% (pleuresia 17%, pneumonia 4%). Gastro intestinal manifestations in 17%, hepatic manifestations in11%, splenomegalia 8%. Hematologic Manifestations in 85% (leucopenia 26%, total lymphopenia 9%, thrombocytopenia 10%, anemia 22%, coombs positive 2.3%). Immunologic Manifestations: LE cells 59%, raised Anti DNA 68%, positive VDRL 18%, FANA 86%, low CH50 46%, low C3 42%, low C4 56%, RF 37%, and CRP were seen in 52% of patients.