Background and objective: To study severe infectious complications in a cohort of patients with systemic lupus erythematosus (SLE). Patients and method: Retrospective study of 705 patients followed from January 1980 to January 2008. Data are expressed in percentages. Results: The frequency of severe infectious was 38,6%. The etiology was bacterial 54,4%, viric 30,4% and opportunist in 15,2% patients. Involved organs were: Lung 38,2%, kidney 48,9%, central nervous system 43%. 43,75% patients received pulsed ciclofosfamide therapy and 88,6% received glucocorticoids (39,7% pulsed). The mortality was 27,7%. Conclusions: At present, infection is an important cause of mortality in patients with SLE. Early diagnosis of infectious complications is very important in SLE. (C) 2009 Elsevier Espana, S.L. All rights reserved.