Abstract Background Comparing cases of adult onset and late onset systemic lupus erythematous (SLE) reveals significant differences in clinical, serological, disease activity, and damage score. Objective This study aimed to analyze clinical manifestations, laboratory data, serological markers, and prognosis of late-onset SLE (L-SLE) and for comparing with adult- onset SLE. Patients and Methods One hundred fifty individuals with SLE were included in a cross-sectional study conducted at Ain Shams University Hospital divide into Group 1: 100 cases with adult-onset (age of onset ≥ 19 years and below 50 years). Group 2: 50 Patients with L-SLE (age of onset ≥ 50 years). All patients were subjected to medical history, physical examination, disease activity measured by the SLE disease activity index (SLEDAI-2K) and a damage score. Laboratory investigations as complete blood count (CBC), serum creatinine, anticardiolipin antibodies, lupus anticoagulant, protein creatinine ratio, serum complement (C3, C4), anti-dsDNA antibody, and antinuclear antibodies (ANA). Results Mucocutaneous manifestations, frequency of hematuria, proteinuria, urinary cast, consumed C3, positive anti-dsDNA antibodies, anti-cardiolipin antibody and lupus anticoagulant titers had considerably greater rates in-group 1 compared to group 2 (P-value <0.05) while group 2 had significantly more musculoskeletal symptoms (P-value <0.05). The SLEDAI scores of the two groups were equivalent, however the damage index was greater in group 2 (P-value 0.00). Neuropsychiatric, cutaneous, renal, and skin damage were more frequent in group 1, while musculoskeletal, endocrinal, pulmonary, cardiovascular and ocular damage were more frequent in- group 2. Conclusion L-SLE is different from adult onset SLE with more frequent damage.