The posterior reversible encephalopathy syndrome (PRES) is a novel entity clinically manifested by headache, changes of sensorium, seizures, and visual loss. PRES pathogenesis has not been fully clarified. The entity can be associated to a variety of clinical conditions, mainly hypertension, renal insufficiency and immunosuppressive therapy. A possible link of autoimmune disorders with PRES has been recently hypothesized. We herein describe two cases of systemic lupus erythematosus whereby PRES was triggered by different factors.