Subject: SLE is an autoimmune disease with skin, joint, renal, cardiovascular, and nervous manifestations. The disease is classified as an immune complex-mediated disease and is characterized by the production of various autoantibodies. Until now, more than 100 autoantibodies have been identified. Patients and methods: This study was performed on 200 SLE patients. All of them were females and their ages ranged from 20 to 49 years. All participants in this study were subjected to physical examination, thorough history taking including age, sex, age of onset, duration of SLE disease, family history, and SLEDAI. Laboratory investigations included: CBC, ESR, liver function tests, renal function tests, ANA, Anti-dsDNA, CRP, Complements C3, C4, and Anti-NCS. Results: There was a highly significant inverse correlation between anti-NCS antibodies and Hb level, a significant direct correlation between anti-NCS antibodies and 24hr proteinuria, a significant inverse correlation between anti-NCS antibodies and complements (C3 and C4), a significant correlation between anti-NCS antibodies and anti dsDNA antibodies, a significant correlation between anti-NCS and disease activity, SLEDAI, and renal affection. Conclusion: Anti-NCS antibody can be a useful tool in the diagnosis of SLE especially in patients who are negative for anti-ds DNA antibodies.