Abstract: Aim: To investigate the impact of gender on expression of systemic lupus erythematosus (SLE) in a cohort of 2355 SLE patients as one of the largest series of cases among the present reports. Method: In this retrospective study we used medical records of all patients (239 male and 2116 female) of the SLE registry of Rheumatology Research Center (RRC), Tehran University of Medical science (TUMS), Iran. Both clinical and paraclinical manifestations of SLE patients have been registered in this database since 1976 and updated during their follow-up. Chi-square test was used to compare the clinical and paraclinical manifestations in men and women at disease onset and during the disease course. We used logistic regression to compute odds ratios with 95% confidence intervals. A P-value < 0.05 was considered as statistically significant. Results: Mean age at disease onset was 25  11.8 and 24.5  10.3 years in men and women, respectively (P = 0.48). Comparison of clinical and immunological manifestations showed that male patients had a higher prevalence of mucocutaneous (43.5% vs. 33.7%, P = 0.005) and a lower prevalence of musculoskeletal symptoms (44% vs. 54.7%, P = 0.003) as the initial manifestation. During the disease course, discoid rash (25.9% vs. 13%, P = 0.000) and type IV lupus nephritis (23.4% vs. 18.1%, P = 0.03) were significantly more common, whereas arthritis (61.1% vs. 71.7%, P = 0.01) and leukopenia (28.5% vs. 35.8%, P = 0.024) were significantly less common in men. Conclusion: This study reveals gender influence on some manifestations of SLE. Considering sex differences is recommended in diagnostic and therapeutic features of the disease. Key words: clinical manifestations, male, systemic lupus erythematosus.