In this review of 159 pts with systemic lupus erythematosus (SLE) followed for 18 years, 78 pts had major infections (20/100 pt-years). Patients with infection had a higher incidence of proteinuria, central nervous system involvement, the use of methylprednisolone boluses and mortality rate. Infection was independent of the amount of steroids and immunosuppressor drugs used. Microorganisms were isolated in 77% of the cases, gram negative enterobacteria were the most common isolates. 30% of the pts had pulmonary infection; and 84% of the infections happened during steroid therapy. Immunosuppression was associated to repeated infections. The 19 pts with fatal infections had a higher frequency of pneumonia and septicemia, and received high doses of steroids (> or = 40 mg). No relation to immunosuppression was found in this group. In 26% opportunistic microorganisms were isolated in association to the use of high doses of steroids. Even if survival of SLE has improved in the last 40 years, infections are still an important cause of mortality, most of them related to aggressive steroid therapy.