We report a 22-year-old woman who developed systemic lupus erythematosus (SLE) immediately after an Epstein-Barr virus (EBV)-induced mononucleosis infection. The link between these two conditions has long been suspected. The close temporal relationship, the course of the pathological events and the development of immunological changes in this case provide further evidence supporting the hypothesis that EBV infection could work as a trigger in some cases of SLE, particularly if the patient is genetically susceptible.