Abstract: Objectives: The aim of this study is to analyze the clinical features, laboratory findings and type of treatments in late onset SLE (after 50 years) in Iranian patients and compare them with the early onset. Methods: Records of 1419 SLE patients who attended our lupus unit, between 1975 and 1999 were reviewed. Nineteen Patients with late onset disease were identified. For comparison, 47 patients with disease onset before the age of 50 were selected by a simple random sampling method from 1400 SLE patients. Clinical features and laboratory findings as included in the 1982 ACR revised criteria for classification of SLE analyzed and compared among these two groups. Both groups had a comparable duration of follow up. Results: In 19 (1.3 %) of 1419 patients in this study, the onset of disease was over the age 50. There were no significant differences in the sex distribution, presenting features and clinical manifestations between the two groups. Lymphopenia and Rheumatoid factor were more frequent in elderly patients (p<0.05) while AntiDNA was less frequent in older patients (p<0.05). There was no significant difference in the use of steroids and cytotoxic agents for the disease control between the two groups. Conclusion: 1. The sex distribution, initial presentations and clinical features of SLE were not influenced by the age. 2. Lymphopenia and Rheumatoid factor were more frequent in elderly patients (p<0.05) while Anti-DNA was less frequently in older patients (p<0.05).